Experimental JGit-based GC Executor

16 files changed, 442 insertions, 40 deletions

diff --git a/src/com/gitblit/AccessRestrictionFilter.java b/src/com/gitblit/AccessRestrictionFilter.java
index 78d33d21..495d3438 100644
--- a/src/com/gitblit/AccessRestrictionFilter.java
+++ b/src/com/gitblit/AccessRestrictionFilter.java
@@ -125,6 +125,12 @@ public abstract class AccessRestrictionFilter extends AuthenticationFilter {
 

 		String fullUrl = getFullUrl(httpRequest);

 		String repository = extractRepositoryName(fullUrl);

+		

+		if (GitBlit.self().isCollectingGarbage(repository)) {

+			logger.info(MessageFormat.format("ARF: Rejecting request for {0}, busy collecting garbage!", repository));

+			httpResponse.sendError(HttpServletResponse.SC_FORBIDDEN);

+			return;

+		}

 

 		// Determine if the request URL is restricted

 		String fullSuffix = fullUrl.substring(repository.length());

diff --git a/src/com/gitblit/Constants.java b/src/com/gitblit/Constants.java
index 33cf2873..f74317ea 100644
--- a/src/com/gitblit/Constants.java
+++ b/src/com/gitblit/Constants.java
@@ -86,6 +86,8 @@ public class Constants {
 	

 	public static final String CONFIG_CUSTOM_FIELDS = "customFields";

 	

+	public static final String ISO8601 = "yyyy-MM-dd'T'HH:mm:ssZ";

+	

 	public static String getGitBlitVersion() {

 		return NAME + " v" + VERSION;

 	}

@@ -384,6 +386,14 @@ public class Constants {
 		REPOSITORY, USER, TEAM;

 	}

 	

+	public static enum GCStatus {

+		READY, COLLECTING;

+		

+		public boolean exceeds(GCStatus s) {

+			return ordinal() > s.ordinal();

+		}

+	}

+	

 	@Documented

 	@Retention(RetentionPolicy.RUNTIME)

 	public @interface Unused {

diff --git a/src/com/gitblit/DownloadZipServlet.java b/src/com/gitblit/DownloadZipServlet.java
index 209272f2..26559344 100644
--- a/src/com/gitblit/DownloadZipServlet.java
+++ b/src/com/gitblit/DownloadZipServlet.java
@@ -101,11 +101,16 @@ public class DownloadZipServlet extends HttpServlet {
 			if (!StringUtils.isEmpty(objectId)) {

 				name += "-" + objectId;

 			}

-

+						

 			Repository r = GitBlit.self().getRepository(repository);

 			if (r == null) {

-				error(response, MessageFormat.format("# Error\nFailed to find repository {0}", repository));

-				return;

+				if (GitBlit.self().isCollectingGarbage(repository)) {

+					error(response, MessageFormat.format("# Error\nGitblit is busy collecting garbage in {0}", repository));

+					return;

+				} else {

+					error(response, MessageFormat.format("# Error\nFailed to find repository {0}", repository));

+					return;

+				}

 			}

 			RevCommit commit = JGitUtils.getCommit(r, objectId);

 			if (commit == null) {

diff --git a/src/com/gitblit/FederationPullExecutor.java b/src/com/gitblit/FederationPullExecutor.java
index 19afacc7..ad1022cf 100644
--- a/src/com/gitblit/FederationPullExecutor.java
+++ b/src/com/gitblit/FederationPullExecutor.java
@@ -189,11 +189,17 @@ public class FederationPullExecutor implements Runnable {
 							repositoryName.indexOf(DOT_GIT_EXT));

 				}

 			}

-

+			

 			// confirm that the origin of any pre-existing repository matches

 			// the clone url

 			String fetchHead = null;

 			Repository existingRepository = GitBlit.self().getRepository(repositoryName);

+			

+			if (existingRepository == null && GitBlit.self().isCollectingGarbage(repositoryName)) {

+				logger.warn(MessageFormat.format("Skipping local repository {0}, busy collecting garbage", repositoryName));

+				continue;

+			}

+

 			if (existingRepository != null) {

 				StoredConfig config = existingRepository.getConfig();

 				config.load();

diff --git a/src/com/gitblit/GCExecutor.java b/src/com/gitblit/GCExecutor.java
new file mode 100644
index 00000000..c5fe43b4
--- /dev/null
+++ b/src/com/gitblit/GCExecutor.java
@@ -0,0 +1,229 @@
+/*

+ * Copyright 2012 gitblit.com.

+ *

+ * Licensed under the Apache License, Version 2.0 (the "License");

+ * you may not use this file except in compliance with the License.

+ * You may obtain a copy of the License at

+ *

+ *     http://www.apache.org/licenses/LICENSE-2.0

+ *

+ * Unless required by applicable law or agreed to in writing, software

+ * distributed under the License is distributed on an "AS IS" BASIS,

+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

+ * See the License for the specific language governing permissions and

+ * limitations under the License.

+ */

+package com.gitblit;

+

+import java.lang.reflect.Field;

+import java.text.MessageFormat;

+import java.util.Calendar;

+import java.util.Date;

+import java.util.Map;

+import java.util.concurrent.ConcurrentHashMap;

+import java.util.concurrent.atomic.AtomicBoolean;

+import java.util.concurrent.atomic.AtomicInteger;

+

+import org.eclipse.jgit.lib.Repository;

+import org.eclipse.jgit.storage.file.FileRepository;

+import org.eclipse.jgit.storage.file.GC;

+import org.eclipse.jgit.storage.file.GC.RepoStatistics;

+import org.slf4j.Logger;

+import org.slf4j.LoggerFactory;

+

+import com.gitblit.models.RepositoryModel;

+import com.gitblit.utils.FileUtils;

+import com.gitblit.utils.TimeUtils;

+

+/**

+ * The GC executor handles periodic garbage collection in repositories.

+ * 

+ * @author James Moger

+ * 

+ */

+public class GCExecutor implements Runnable {

+

+	public static enum GCStatus {

+		READY, COLLECTING;

+		

+		public boolean exceeds(GCStatus s) {

+			return ordinal() > s.ordinal();

+		}

+	}

+	private final Logger logger = LoggerFactory.getLogger(GCExecutor.class);

+

+	private final IStoredSettings settings;

+	

+	private AtomicBoolean forceClose = new AtomicBoolean(false);

+	

+	private final Map<String, GCStatus> gcCache = new ConcurrentHashMap<String, GCStatus>();

+

+	public GCExecutor(IStoredSettings settings) {

+		this.settings = settings;

+	}

+

+	/**

+	 * Indicates if the GC executor is ready to process repositories.

+	 * 

+	 * @return true if the GC executor is ready to process repositories

+	 */

+	public boolean isReady() {

+		return settings.getBoolean(Keys.git.enableGarbageCollection, false);

+	}

+	

+	public boolean lock(String repositoryName) {

+		return setGCStatus(repositoryName, GCStatus.COLLECTING);

+	}

+

+	/**

+	 * Tries to set a GCStatus for the specified repository.

+	 * 

+	 * @param repositoryName

+	 * @return true if the status has been set

+	 */

+	private boolean setGCStatus(String repositoryName, GCStatus status) {

+		String key = repositoryName.toLowerCase();

+		if (gcCache.containsKey(key)) {

+			if (gcCache.get(key).exceeds(GCStatus.READY)) {

+				// already collecting or blocked

+				return false;

+			}

+		}

+		gcCache.put(key, status);

+		return true;

+	}

+

+	/**

+	 * Returns true if Gitblit is actively collecting garbage in this repository.

+	 * 

+	 * @param repositoryName

+	 * @return true if actively collecting garbage

+	 */

+	public boolean isCollectingGarbage(String repositoryName) {

+		String key = repositoryName.toLowerCase();

+		return gcCache.containsKey(key) && GCStatus.COLLECTING.equals(gcCache.get(key));

+	}

+

+	/**

+	 * Resets the GC status to ready.

+	 * 

+	 * @param repositoryName

+	 */

+	public void releaseLock(String repositoryName) {

+		gcCache.put(repositoryName.toLowerCase(), GCStatus.READY);

+	}

+	

+	public void close() {

+		forceClose.set(true);

+	}

+

+	@Override

+	public void run() {

+		if (!isReady()) {

+			return;

+		}

+		Date now = new Date();

+

+		for (String repositoryName : GitBlit.self().getRepositoryList()) {

+			if (forceClose.get()) {

+				break;

+			}

+			if (isCollectingGarbage(repositoryName)) {

+				logger.warn(MessageFormat.format("Already collecting garbage from {0}?!?", repositoryName));

+				continue;

+			}

+			boolean garbageCollected = false;

+			RepositoryModel model = null;

+			FileRepository repository = null;

+			try {

+				model = GitBlit.self().getRepositoryModel(repositoryName);

+				repository = (FileRepository) GitBlit.self().getRepository(repositoryName);

+				if (repository == null) {

+					logger.warn(MessageFormat.format("GCExecutor is missing repository {0}?!?", repositoryName));

+					continue;

+				}

+				

+				if (!isRepositoryIdle(repository)) {

+					logger.debug(MessageFormat.format("GCExecutor is skipping {0} because it is not idle", repositoryName));

+					continue;

+				}

+

+				// By setting the GCStatus to COLLECTING we are

+				// disabling *all* access to this repository from Gitblit.

+				// Think of this as a clutch in a manual transmission vehicle.

+				if (!setGCStatus(repositoryName, GCStatus.COLLECTING)) {

+					logger.warn(MessageFormat.format("Can not acquire GC lock for {0}, skipping", repositoryName));

+					continue;

+				}

+				

+				logger.debug(MessageFormat.format("GCExecutor locked idle repository {0}", repositoryName));

+				

+				GC gc = new GC(repository);

+				RepoStatistics stats = gc.getStatistics();

+				

+				// determine if this is a scheduled GC

+				int gcPeriodInDays = TimeUtils.convertFrequencyToMinutes(model.gcPeriod)/(60*24);

+				Calendar cal = Calendar.getInstance();

+				cal.setTime(model.lastGC);

+				cal.set(Calendar.HOUR_OF_DAY, 0);

+				cal.set(Calendar.MINUTE, 0);

+				cal.set(Calendar.SECOND, 0);

+				cal.set(Calendar.MILLISECOND, 0);

+				cal.add(Calendar.DATE, gcPeriodInDays);

+				Date gcDate = cal.getTime();

+				boolean shouldCollectGarbage = now.after(gcDate);

+

+				// determine if filesize triggered GC

+				long gcThreshold = FileUtils.convertSizeToLong(model.gcThreshold, 500*1024L);

+				boolean hasEnoughGarbage = stats.sizeOfLooseObjects >= gcThreshold;

+

+				// if we satisfy one of the requirements, GC

+				boolean hasGarbage = stats.sizeOfLooseObjects > 0;

+				if (hasGarbage && (hasEnoughGarbage || shouldCollectGarbage)) {

+					long looseKB = stats.sizeOfLooseObjects/1024L;

+					logger.info(MessageFormat.format("Collecting {1} KB of loose objects from {0}", repositoryName, looseKB));

+					

+					// do the deed

+					gc.gc();

+					

+					garbageCollected = true;

+				}

+			} catch (Exception e) {

+				logger.error("Error collecting garbage in " + repositoryName, e);

+			} finally {

+				// cleanup

+				if (repository != null) {

+					if (garbageCollected) {

+						// update the last GC date

+						model.lastGC = new Date();

+						GitBlit.self().updateConfiguration(repository, model);

+					}

+				

+					repository.close();

+				}

+				

+				// reset the GC lock 

+				releaseLock(repositoryName);

+				logger.debug(MessageFormat.format("GCExecutor released GC lock for {0}", repositoryName));

+			}

+		}

+	}

+	

+	private boolean isRepositoryIdle(FileRepository repository) {

+		try {

+			// Read the use count.

+			// An idle use count is 2:

+			// +1 for being in the cache

+			// +1 for the repository parameter in this method

+			Field useCnt = Repository.class.getDeclaredField("useCnt");

+			useCnt.setAccessible(true);

+			int useCount = ((AtomicInteger) useCnt.get(repository)).get();

+			return useCount == 2;

+		} catch (Exception e) {

+			logger.warn(MessageFormat

+					.format("Failed to reflectively determine use count for repository {0}",

+							repository.getDirectory().getPath()), e);

+		}

+		return false;

+	}

+}

diff --git a/src/com/gitblit/GitBlit.java b/src/com/gitblit/GitBlit.java
index e83da933..402f600d 100644
--- a/src/com/gitblit/GitBlit.java
+++ b/src/com/gitblit/GitBlit.java
@@ -28,6 +28,7 @@ import java.text.MessageFormat;
 import java.text.SimpleDateFormat;

 import java.util.ArrayList;

 import java.util.Arrays;

+import java.util.Calendar;

 import java.util.Collection;

 import java.util.Collections;

 import java.util.Date;

@@ -103,6 +104,7 @@ import com.gitblit.utils.JsonUtils;
 import com.gitblit.utils.MetricUtils;

 import com.gitblit.utils.ObjectCache;

 import com.gitblit.utils.StringUtils;

+import com.gitblit.utils.TimeUtils;

 import com.gitblit.wicket.WicketUtils;

 

 /**

@@ -160,6 +162,8 @@ public class GitBlit implements ServletContextListener {
 	

 	private LuceneExecutor luceneExecutor;

 	

+	private GCExecutor gcExecutor;

+	

 	private TimeZone timezone;

 	

 	private FileBasedConfig projectConfigs;

@@ -251,6 +255,34 @@ public class GitBlit implements ServletContextListener {
 	public static int getInteger(String key, int defaultValue) {

 		return self().settings.getInteger(key, defaultValue);

 	}

+	

+	/**

+	 * Returns the value in bytes for the specified key. If the key does not

+	 * exist or the value for the key can not be interpreted as an integer, the

+	 * defaultValue is returned.

+	 * 

+	 * @see IStoredSettings.getFilesize(String key, int defaultValue)

+	 * @param key

+	 * @param defaultValue

+	 * @return key value or defaultValue

+	 */

+	public static int getFilesize(String key, int defaultValue) {

+		return self().settings.getFilesize(key, defaultValue);

+	}

+

+	/**

+	 * Returns the value in bytes for the specified key. If the key does not

+	 * exist or the value for the key can not be interpreted as a long, the

+	 * defaultValue is returned.

+	 * 

+	 * @see IStoredSettings.getFilesize(String key, long defaultValue)

+	 * @param key

+	 * @param defaultValue

+	 * @return key value or defaultValue

+	 */

+	public static long getFilesize(String key, long defaultValue) {

+		return self().settings.getFilesize(key, defaultValue);

+	}

 

 	/**

 	 * Returns the char value for the specified key. If the key does not exist

@@ -1018,10 +1050,15 @@ public class GitBlit implements ServletContextListener {
 	 * @return repository or null

 	 */

 	public Repository getRepository(String repositoryName, boolean logError) {

+		if (isCollectingGarbage(repositoryName)) {

+			logger.warn(MessageFormat.format("Rejecting request for {0}, busy collecting garbage!", repositoryName));

+			return null;

+		}

+

 		File dir = FileKey.resolve(new File(repositoriesFolder, repositoryName), FS.DETECTED);

 		if (dir == null)

 			return null;

-

+		

 		Repository r = null;

 		try {

 			FileKey key = FileKey.exact(dir, FS.DETECTED);

@@ -1115,7 +1152,14 @@ public class GitBlit implements ServletContextListener {
 		

 		// cached model

 		RepositoryModel model = repositoryListCache.get(repositoryName);

-		

+

+		if (gcExecutor.isCollectingGarbage(model.name)) {

+			// Gitblit is busy collecting garbage, use our cached model

+			RepositoryModel rm = DeepCopier.copy(model);

+			rm.isCollectingGarbage = true;

+			return rm;

+		}

+

 		// check for updates

 		Repository r = getRepository(repositoryName);

 		if (r == null) {

@@ -1180,12 +1224,6 @@ public class GitBlit implements ServletContextListener {
 				}

 				project.title = projectConfigs.getString("project", name, "title");

 				project.description = projectConfigs.getString("project", name, "description");

-				// TODO add more interesting metadata

-				// project manager?

-				// commit message regex?

-				// RW+

-				// RW

-				// R

 				configs.put(name.toLowerCase(), project);				

 			}

 			projectCache.clear();

@@ -1379,6 +1417,13 @@ public class GitBlit implements ServletContextListener {
 			model.federationSets = new ArrayList<String>(Arrays.asList(config.getStringList(

 					Constants.CONFIG_GITBLIT, null, "federationSets")));

 			model.isFederated = getConfig(config, "isFederated", false);

+			model.gcThreshold = getConfig(config, "gcThreshold", settings.getString(Keys.git.defaultGarbageCollectionThreshold, "500KB"));

+			model.gcPeriod = getConfig(config, "gcPeriod", settings.getString(Keys.git.defaultGarbageCollectionPeriod, "7 days"));

+			try {

+				model.lastGC = new SimpleDateFormat(Constants.ISO8601).parse(getConfig(config, "lastGC", "1970-01-01'T'00:00:00Z"));

+			} catch (Exception e) {

+				model.lastGC = new Date(0);

+			}

 			model.origin = config.getString("remote", "origin", "url");

 			if (model.origin != null) {

 				model.origin = model.origin.replace('\\', '/');

@@ -1675,6 +1720,10 @@ public class GitBlit implements ServletContextListener {
 	 */

 	public void updateRepositoryModel(String repositoryName, RepositoryModel repository,

 			boolean isCreate) throws GitBlitException {

+		if (gcExecutor.isCollectingGarbage(repositoryName)) {

+			throw new GitBlitException(MessageFormat.format("sorry, Gitblit is busy collecting garbage in {0}",

+					repositoryName));

+		}

 		Repository r = null;

 		String projectPath = StringUtils.getFirstPathElement(repository.name);

 		if (!StringUtils.isEmpty(projectPath)) {

@@ -1819,6 +1868,9 @@ public class GitBlit implements ServletContextListener {
 		config.setString(Constants.CONFIG_GITBLIT, null, "federationStrategy",

 				repository.federationStrategy.name());

 		config.setBoolean(Constants.CONFIG_GITBLIT, null, "isFederated", repository.isFederated);

+		config.setString(Constants.CONFIG_GITBLIT, null, "gcThreshold", repository.gcThreshold);

+		config.setString(Constants.CONFIG_GITBLIT, null, "gcPeriod", repository.gcPeriod);

+		config.setString(Constants.CONFIG_GITBLIT, null, "lastGC", new SimpleDateFormat(Constants.ISO8601).format(repository.lastGC));

 

 		updateList(config, "federationSets", repository.federationSets);

 		updateList(config, "preReceiveScript", repository.preReceiveScripts);

@@ -2614,6 +2666,12 @@ public class GitBlit implements ServletContextListener {
 	public void configureContext(IStoredSettings settings, boolean startFederation) {

 		logger.info("Reading configuration from " + settings.toString());

 		this.settings = settings;

+		

+		// prepare service executors

+		mailExecutor = new MailExecutor(settings);

+		luceneExecutor = new LuceneExecutor(settings, repositoriesFolder);

+		gcExecutor = new GCExecutor(settings);

+		

 		repositoriesFolder = getRepositoriesFolder();

 		logger.info("Git repositories folder " + repositoriesFolder.getAbsolutePath());

 

@@ -2647,16 +2705,43 @@ public class GitBlit implements ServletContextListener {
 		// load and cache the project metadata

 		projectConfigs = new FileBasedConfig(getFileOrFolder(Keys.web.projectsFile, "projects.conf"), FS.detect());

 		getProjectConfigs();

-		mailExecutor = new MailExecutor(settings);

+		

+		// schedule mail engine

 		if (mailExecutor.isReady()) {

 			logger.info("Mail executor is scheduled to process the message queue every 2 minutes.");

 			scheduledExecutor.scheduleAtFixedRate(mailExecutor, 1, 2, TimeUnit.MINUTES);

 		} else {

 			logger.warn("Mail server is not properly configured.  Mail services disabled.");

 		}

-		luceneExecutor = new LuceneExecutor(settings, repositoriesFolder);

+		

+		// schedule lucene engine

 		logger.info("Lucene executor is scheduled to process indexed branches every 2 minutes.");

 		scheduledExecutor.scheduleAtFixedRate(luceneExecutor, 1, 2, TimeUnit.MINUTES);

+		

+		// schedule gc engine

+		if (gcExecutor.isReady()) {

+			logger.info("GC executor is scheduled to scan repositories every 24 hours.");

+			Calendar c = Calendar.getInstance();

+			c.set(Calendar.HOUR_OF_DAY, settings.getInteger(Keys.git.garbageCollectionHour, 0));

+			c.set(Calendar.MINUTE, 0);

+			c.set(Calendar.SECOND, 0);

+			c.set(Calendar.MILLISECOND, 0);

+			Date cd = c.getTime();

+			Date now = new Date();

+			int delay = 0;

+			if (cd.before(now)) {

+				c.add(Calendar.DATE, 1);

+				cd = c.getTime();

+			}

+			delay = (int) ((cd.getTime() - now.getTime())/TimeUtils.MIN);

+			String when = delay + " mins";

+			if (delay > 60) {

+				when = MessageFormat.format("{0,number,0.0} hours", ((float)delay)/60f);

+			}

+			logger.info(MessageFormat.format("Next scheculed GC scan is in {0}", when));

+			scheduledExecutor.scheduleAtFixedRate(gcExecutor, delay, 60*24, TimeUnit.MINUTES);

+		}

+		

 		if (startFederation) {

 			configureFederation();

 		}

@@ -2758,9 +2843,20 @@ public class GitBlit implements ServletContextListener {
 		logger.info("Gitblit context destroyed by servlet container.");

 		scheduledExecutor.shutdownNow();

 		luceneExecutor.close();

+		gcExecutor.close();

 	}

 	

 	/**

+	 * Returns true if Gitblit is actively collecting garbage in this repository.

+	 * 

+	 * @param repositoryName

+	 * @return true if actively collecting garbage

+	 */

+	public boolean isCollectingGarbage(String repositoryName) {

+		return gcExecutor.isCollectingGarbage(repositoryName);

+	}

+

+	/**

 	 * Creates a personal fork of the specified repository. The clone is view

 	 * restricted by default and the owner of the source repository is given

 	 * access to the clone. 

diff --git a/src/com/gitblit/LuceneExecutor.java b/src/com/gitblit/LuceneExecutor.java
index 42155f42..dffd4788 100644
--- a/src/com/gitblit/LuceneExecutor.java
+++ b/src/com/gitblit/LuceneExecutor.java
@@ -171,6 +171,12 @@ public class LuceneExecutor implements Runnable {
 			RepositoryModel model = GitBlit.self().getRepositoryModel(repositoryName);

 			if (model.hasCommits && !ArrayUtils.isEmpty(model.indexedBranches)) {

 				Repository repository = GitBlit.self().getRepository(model.name);

+				if (repository == null) {

+					if (GitBlit.self().isCollectingGarbage(model.name)) {

+						logger.info(MessageFormat.format("Skipping Lucene index of {0}, busy garbage collecting", repositoryName));

+					}

+					continue;

+				}

 				index(model, repository);				

 				repository.close();

 				System.gc();

diff --git a/src/com/gitblit/RpcServlet.java b/src/com/gitblit/RpcServlet.java
index 0c9ac379..f6368dd0 100644
--- a/src/com/gitblit/RpcServlet.java
+++ b/src/com/gitblit/RpcServlet.java
@@ -110,6 +110,11 @@ public class RpcServlet extends JsonServlet {
 					// skip empty repository

 					continue;

 				}

+				if (model.isCollectingGarbage) {

+					// skip garbage collecting repository

+					logger.warn(MessageFormat.format("Temporarily excluding {0} from RPC, busy collecting garbage", model.name));

+					continue;

+				}

 				// get local branches

 				Repository repository = GitBlit.self().getRepository(model.name);

 				List<RefModel> refs = JGitUtils.getLocalBranches(repository, false, -1);

diff --git a/src/com/gitblit/SyndicationServlet.java b/src/com/gitblit/SyndicationServlet.java
index a36f5839..baaf7eb7 100644
--- a/src/com/gitblit/SyndicationServlet.java
+++ b/src/com/gitblit/SyndicationServlet.java
@@ -210,7 +210,13 @@ public class SyndicationServlet extends HttpServlet {
 		for (String name : repositories) {

 			Repository repository = GitBlit.self().getRepository(name);

 			RepositoryModel model = GitBlit.self().getRepositoryModel(name);

-			

+

+			if (repository == null) {

+				if (model.isCollectingGarbage) {

+					logger.warn(MessageFormat.format("Temporarily excluding {0} from feed, busy collecting garbage", name));

+				} 

+				continue;

+			}

 			if (!isProjectFeed) {

 				// single-repository feed

 				feedName = model.name;

diff --git a/src/com/gitblit/models/RepositoryModel.java b/src/com/gitblit/models/RepositoryModel.java
index 502f886e..23ce9e3b 100644
--- a/src/com/gitblit/models/RepositoryModel.java
+++ b/src/com/gitblit/models/RepositoryModel.java
@@ -76,6 +76,11 @@ public class RepositoryModel implements Serializable, Comparable<RepositoryModel
 	public Set<String> forks;

 	public String originRepository;

 	public boolean verifyCommitter;

+	public String gcThreshold;

+	public String gcPeriod;

+	

+	public transient boolean isCollectingGarbage;

+	public Date lastGC;

 	

 	public RepositoryModel() {

 		this("", "", "", new Date(0));

diff --git a/src/com/gitblit/utils/ActivityUtils.java b/src/com/gitblit/utils/ActivityUtils.java
index e5159942..e389e642 100644
--- a/src/com/gitblit/utils/ActivityUtils.java
+++ b/src/com/gitblit/utils/ActivityUtils.java
@@ -82,6 +82,9 @@ public class ActivityUtils {
 		Map<String, Activity> activity = new HashMap<String, Activity>();

 		for (RepositoryModel model : models) {

 			if (model.hasCommits && model.lastChange.after(thresholdDate)) {

+				if (model.isCollectingGarbage) {

+					continue;

+				}

 				Repository repository = GitBlit.self()

 						.getRepository(model.name);

 				List<String> branches = new ArrayList<String>();

diff --git a/src/com/gitblit/wicket/GitBlitWebApp.properties b/src/com/gitblit/wicket/GitBlitWebApp.properties
index 09ee929b..62e4817f 100644
--- a/src/com/gitblit/wicket/GitBlitWebApp.properties
+++ b/src/com/gitblit/wicket/GitBlitWebApp.properties
@@ -357,4 +357,10 @@ gb.createPermission = {0} (push, ref creation)
 gb.deletePermission = {0} (push, ref creation+deletion)

 gb.rewindPermission = {0} (push, ref creation+deletion+rewind)

 gb.permission = permission

-gb.regexPermission = this permission is set from a regular expression
\ No newline at end of file
+gb.regexPermission = this permission is set from a regular expression

+gb.accessDenied = access denied

+gb.busyCollectingGarbage = sorry, Gitblit is busy collecting garbage in {0}

+gb.gcPeriod = GC period

+gb.gcPeriodDescription = duration between garbage collections

+gb.gcThreshold = GC threshold

+gb.gcThresholdDescription = minimum total size of loose objects to trigger early garbage collection

diff --git a/src/com/gitblit/wicket/pages/EditRepositoryPage.html b/src/com/gitblit/wicket/pages/EditRepositoryPage.html
index 23e2312f..7bd896cf 100644
--- a/src/com/gitblit/wicket/pages/EditRepositoryPage.html
+++ b/src/com/gitblit/wicket/pages/EditRepositoryPage.html
@@ -28,15 +28,17 @@
 				<tr><th><wicket:message key="gb.name"></wicket:message></th><td class="edit"><input class="span4" type="text" wicket:id="name" id="name" size="40" tabindex="1" /> &nbsp;<span class="help-inline"><wicket:message key="gb.nameDescription"></wicket:message></span></td></tr>

 				<tr><th><wicket:message key="gb.description"></wicket:message></th><td class="edit"><input class="span4" type="text" wicket:id="description" size="40" tabindex="2" /></td></tr>

 				<tr><th><wicket:message key="gb.origin"></wicket:message></th><td class="edit"><input class="span5" type="text" wicket:id="origin" size="80" tabindex="3" /></td></tr>

-				<tr><th><wicket:message key="gb.headRef"></wicket:message></th><td class="edit"><select wicket:id="HEAD" tabindex="4" /> &nbsp;<span class="help-inline"><wicket:message key="gb.headRefDescription"></wicket:message></span></td></tr>

-				<tr><th><wicket:message key="gb.owner"></wicket:message></th><td class="edit"><select wicket:id="owner" tabindex="5" /> &nbsp;<span class="help-inline"><wicket:message key="gb.ownerDescription"></wicket:message></span></td></tr>

-				<tr><th><wicket:message key="gb.enableTickets"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="useTickets" tabindex="6" /> &nbsp;<span class="help-inline"><wicket:message key="gb.useTicketsDescription"></wicket:message></span></label></td></tr>

-				<tr><th><wicket:message key="gb.enableDocs"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="useDocs" tabindex="7" /> &nbsp;<span class="help-inline"><wicket:message key="gb.useDocsDescription"></wicket:message></span></label></td></tr>

-				<tr><th><wicket:message key="gb.showRemoteBranches"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="showRemoteBranches" tabindex="8" /> &nbsp;<span class="help-inline"><wicket:message key="gb.showRemoteBranchesDescription"></wicket:message></span></label></td></tr>

-				<tr><th><wicket:message key="gb.showReadme"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="showReadme" tabindex="9" /> &nbsp;<span class="help-inline"><wicket:message key="gb.showReadmeDescription"></wicket:message></span></label></td></tr>

-				<tr><th><wicket:message key="gb.skipSizeCalculation"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="skipSizeCalculation" tabindex="10" /> &nbsp;<span class="help-inline"><wicket:message key="gb.skipSizeCalculationDescription"></wicket:message></span></label></td></tr>

-				<tr><th><wicket:message key="gb.skipSummaryMetrics"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="skipSummaryMetrics" tabindex="11" /> &nbsp;<span class="help-inline"><wicket:message key="gb.skipSummaryMetricsDescription"></wicket:message></span></label></td></tr>

-				<tr><th><wicket:message key="gb.mailingLists"></wicket:message></th><td class="edit"><input class="span8" type="text" wicket:id="mailingLists" size="40" tabindex="13" /></td></tr>

+				<tr><th><wicket:message key="gb.headRef"></wicket:message></th><td class="edit"><select class="span3" wicket:id="HEAD" tabindex="4" /> &nbsp;<span class="help-inline"><wicket:message key="gb.headRefDescription"></wicket:message></span></td></tr>

+				<tr><th><wicket:message key="gb.owner"></wicket:message></th><td class="edit"><select class="span2" wicket:id="owner" tabindex="5" /> &nbsp;<span class="help-inline"><wicket:message key="gb.ownerDescription"></wicket:message></span></td></tr>

+				<tr><th><wicket:message key="gb.gcPeriod"></wicket:message></th><td class="edit"><select class="span2" wicket:id="gcPeriod" tabindex="6" /> &nbsp;<span class="help-inline"><wicket:message key="gb.gcPeriodDescription"></wicket:message></span></td></tr>

+				<tr><th><wicket:message key="gb.gcThreshold"></wicket:message></th><td class="edit"><input class="span1" type="text" wicket:id="gcThreshold" tabindex="7" /> &nbsp;<span class="help-inline"><wicket:message key="gb.gcThresholdDescription"></wicket:message></span></td></tr>

+				<tr><th><wicket:message key="gb.enableTickets"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="useTickets" tabindex="8" /> &nbsp;<span class="help-inline"><wicket:message key="gb.useTicketsDescription"></wicket:message></span></label></td></tr>

+				<tr><th><wicket:message key="gb.enableDocs"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="useDocs" tabindex="9" /> &nbsp;<span class="help-inline"><wicket:message key="gb.useDocsDescription"></wicket:message></span></label></td></tr>

+				<tr><th><wicket:message key="gb.showRemoteBranches"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="showRemoteBranches" tabindex="10" /> &nbsp;<span class="help-inline"><wicket:message key="gb.showRemoteBranchesDescription"></wicket:message></span></label></td></tr>

+				<tr><th><wicket:message key="gb.showReadme"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="showReadme" tabindex="11" /> &nbsp;<span class="help-inline"><wicket:message key="gb.showReadmeDescription"></wicket:message></span></label></td></tr>

+				<tr><th><wicket:message key="gb.skipSizeCalculation"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="skipSizeCalculation" tabindex="12" /> &nbsp;<span class="help-inline"><wicket:message key="gb.skipSizeCalculationDescription"></wicket:message></span></label></td></tr>

+				<tr><th><wicket:message key="gb.skipSummaryMetrics"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="skipSummaryMetrics" tabindex="13" /> &nbsp;<span class="help-inline"><wicket:message key="gb.skipSummaryMetricsDescription"></wicket:message></span></label></td></tr>

+				<tr><th><wicket:message key="gb.mailingLists"></wicket:message></th><td class="edit"><input class="span8" type="text" wicket:id="mailingLists" size="40" tabindex="14" /></td></tr>

 			</tbody>

 		</table>

 		</div>

@@ -45,18 +47,18 @@
 		<div class="tab-pane" id="permissions">

 			<table class="plain">

 				<tbody class="settings">

-					<tr><th><wicket:message key="gb.accessRestriction"></wicket:message></th><td class="edit"><select class="span4" wicket:id="accessRestriction" tabindex="13" /></td></tr>

+					<tr><th><wicket:message key="gb.accessRestriction"></wicket:message></th><td class="edit"><select class="span4" wicket:id="accessRestriction" tabindex="15" /></td></tr>

 					<tr><th colspan="2"><hr/></th></tr>

 					<tr><th><wicket:message key="gb.authorizationControl"></wicket:message></th><td style="padding:2px;">

 						<wicket:container wicket:id="authorizationControl">

-							<label class="radio"><input type="radio" wicket:id="allowAuthenticated" tabindex="14" /> &nbsp;<span class="help-inline"><wicket:message key="gb.allowAuthenticatedDescription"></wicket:message></span></label>

-							<label class="radio"><input type="radio" wicket:id="allowNamed" tabindex="15" /> &nbsp;<span class="help-inline"><wicket:message key="gb.allowNamedDescription"></wicket:message></span></label>

+							<label class="radio"><input type="radio" wicket:id="allowAuthenticated" tabindex="16" /> &nbsp;<span class="help-inline"><wicket:message key="gb.allowAuthenticatedDescription"></wicket:message></span></label>

+							<label class="radio"><input type="radio" wicket:id="allowNamed" tabindex="17" /> &nbsp;<span class="help-inline"><wicket:message key="gb.allowNamedDescription"></wicket:message></span></label>

 						</wicket:container>

 					</td></tr>

 					<tr><th colspan="2"><hr/></th></tr>

-					<tr><th><wicket:message key="gb.isFrozen"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="isFrozen" tabindex="16" /> &nbsp;<span class="help-inline"><wicket:message key="gb.isFrozenDescription"></wicket:message></span></label></td></tr>

-					<tr><th><wicket:message key="gb.allowForks"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="allowForks" tabindex="17" /> &nbsp;<span class="help-inline"><wicket:message key="gb.allowForksDescription"></wicket:message></span></label></td></tr>

-					<tr><th><wicket:message key="gb.verifyCommitter"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="verifyCommitter" tabindex="18" /> &nbsp;<span class="help-inline"><wicket:message key="gb.verifyCommitterDescription"></wicket:message></span><br/><span class="help-inline" style="padding-left:10px;"><wicket:message key="gb.verifyCommitterNote"></wicket:message></span></label></td></tr>

+					<tr><th><wicket:message key="gb.isFrozen"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="isFrozen" tabindex="18" /> &nbsp;<span class="help-inline"><wicket:message key="gb.isFrozenDescription"></wicket:message></span></label></td></tr>

+					<tr><th><wicket:message key="gb.allowForks"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="allowForks" tabindex="19" /> &nbsp;<span class="help-inline"><wicket:message key="gb.allowForksDescription"></wicket:message></span></label></td></tr>

+					<tr><th><wicket:message key="gb.verifyCommitter"></wicket:message></th><td class="edit"><label class="checkbox"><input type="checkbox" wicket:id="verifyCommitter" tabindex="20" /> &nbsp;<span class="help-inline"><wicket:message key="gb.verifyCommitterDescription"></wicket:message></span><br/><span class="help-inline" style="padding-left:10px;"><wicket:message key="gb.verifyCommitterNote"></wicket:message></span></label></td></tr>

 					<tr><th colspan="2"><hr/></th></tr>

 					<tr><th><wicket:message key="gb.userPermissions"></wicket:message></th><td style="padding:2px;"><span wicket:id="users"></span></td></tr>

 					<tr><th colspan="2"><hr/></th></tr>

@@ -69,7 +71,7 @@
 		<div class="tab-pane" id="federation">

 			<table class="plain">

 				<tbody class="settings">

-					<tr><th><wicket:message key="gb.federationStrategy"></wicket:message></th><td class="edit"><select class="span4" wicket:id="federationStrategy" tabindex="19" /></td></tr>

+					<tr><th><wicket:message key="gb.federationStrategy"></wicket:message></th><td class="edit"><select class="span4" wicket:id="federationStrategy" tabindex="21" /></td></tr>

 					<tr><th><wicket:message key="gb.federationSets"></wicket:message></th><td style="padding:2px;"><span wicket:id="federationSets"></span></td></tr>

 				</tbody>

 			</table>

diff --git a/src/com/gitblit/wicket/pages/EditRepositoryPage.java b/src/com/gitblit/wicket/pages/EditRepositoryPage.java
index 98b04f50..1a2e63ce 100644
--- a/src/com/gitblit/wicket/pages/EditRepositoryPage.java
+++ b/src/com/gitblit/wicket/pages/EditRepositoryPage.java
@@ -379,6 +379,10 @@ public class EditRepositoryPage extends RootSubPage {
 		}

 		form.add(new DropDownChoice<String>("HEAD", availableRefs).setEnabled(availableRefs.size() > 0));

 

+		List<String> gcPeriods = Arrays.asList("1 day", "2 days", "3 days", "4 days", "5 days", "7 days", "10 days", "14 days");

+		form.add(new DropDownChoice<String>("gcPeriod", gcPeriods));

+		form.add(new TextField<String>("gcThreshold"));

+

 		// federation strategies - remove ORIGIN choice if this repository has

 		// no origin.

 		List<FederationStrategy> federationStrategies = new ArrayList<FederationStrategy>(

diff --git a/src/com/gitblit/wicket/pages/RepositoryPage.java b/src/com/gitblit/wicket/pages/RepositoryPage.java
index bacf233d..2bd1ec26 100644
--- a/src/com/gitblit/wicket/pages/RepositoryPage.java
+++ b/src/com/gitblit/wicket/pages/RepositoryPage.java
@@ -92,6 +92,18 @@ public abstract class RepositoryPage extends BasePage {
 		}

 		objectId = WicketUtils.getObject(params);

 		

+		if (StringUtils.isEmpty(repositoryName)) {

+			error(MessageFormat.format(getString("gb.repositoryNotSpecifiedFor"), getPageName()), true);

+		}

+

+		if (!getRepositoryModel().hasCommits) {

+			setResponsePage(EmptyRepositoryPage.class, params);

+		}

+		

+		if (getRepositoryModel().isCollectingGarbage) {

+			error(MessageFormat.format(getString("gb.busyCollectingGarbage"), getRepositoryModel().name), true);

+		}

+

 		if (objectId != null) {

 			RefModel branch = null;

 			if ((branch = JGitUtils.getBranch(getRepository(), objectId)) != null) {

@@ -103,17 +115,10 @@ public abstract class RepositoryPage extends BasePage {
 				boolean canAccess = user.hasBranchPermission(repositoryName,

 								branch.reference.getName());

 				if (!canAccess) {

-					error("Access denied", true);

+					error(getString("gb.accessDeined"), true);

 				}

 			}

 		}

-		if (StringUtils.isEmpty(repositoryName)) {

-			error(MessageFormat.format(getString("gb.repositoryNotSpecifiedFor"), getPageName()), true);

-		}

-

-		if (!getRepositoryModel().hasCommits) {

-			setResponsePage(EmptyRepositoryPage.class, params);

-		}

 

 		// register the available page links for this page and user

 		registeredPages = registerPages();

diff --git a/src/com/gitblit/wicket/panels/BranchesPanel.java b/src/com/gitblit/wicket/panels/BranchesPanel.java
index 3ca02cb6..cfe9f5fe 100644
--- a/src/com/gitblit/wicket/panels/BranchesPanel.java
+++ b/src/com/gitblit/wicket/panels/BranchesPanel.java
@@ -166,6 +166,14 @@ public class BranchesPanel extends BasePanel {
 			@Override

 			public void onClick() {

 				Repository r = GitBlit.self().getRepository(repositoryModel.name);

+				if (r == null) {

+					if (GitBlit.self().isCollectingGarbage(repositoryModel.name)) {

+						error(MessageFormat.format(getString("gb.busyCollectingGarbage"), repositoryModel.name));

+					} else {

+						error(MessageFormat.format("Failed to find repository {0}", repositoryModel.name));

+					}

+					return;

+				}

 				boolean success = JGitUtils.deleteBranchRef(r, entry.getName());

 				r.close();

 				if (success) {