RefDirectory.scanRef: Re-use file existence check done in snapshot creation
Return immediately in scanRef if the loose ref was identified as
missing when a snapshot was attempted for the ref. This will help
performance of scanRef when the ref is packed but has a corresponding
empty dir in 'refs/'.
For example, consider the case where we create 50k sharded refs in
a new namespace called 'new-refs' using an atomic 'BatchRefUpdate'.
The refs are named like 'refs/new-refs/01/1/1', 'refs/new-refs/01/1/2',
'refs/new-refs/01/1/3' and so on. After the refs are created, the
'new-refs' namespace looks like below:
$ find refs/new-refs -type f | wc -l
0
$ find refs/new-refs -type d | wc -l
5101
At this point, an 'exactRef' call on each of the 50k refs without
this change takes ~2.5s, where as with this change it takes ~1.5s.
FileSnapshot: Lazy load file store attributes cache
Doing a getFileStoreAttributes call even when the file doesn't
exist is unnecessary. This call is particularly slow on some
filesystems. Instead, do it only when the file exists and load
the appropriate cache.
This update can help speed up RefDirectory.exactRef when the ref
is packed, but has a corresponding empty dir for it under 'refs/'.
This scenario can happen when an atomic 'BatchRefUpdate' creates
new sharded refs.
For example, consider the case where we create 50k sharded refs in
a new namespace called 'new-refs' using an atomic 'BatchRefUpdate'.
The refs are named like 'refs/new-refs/01/1/1', 'refs/new-refs/01/1/2',
'refs/new-refs/01/1/3' and so on. After the refs are created, the
'new-refs' namespace looks like below:
$ find refs/new-refs -type f | wc -l
0
$ find refs/new-refs -type d | wc -l
5101
At this point, an 'exactRef' call on each of the 50k refs without
this change takes ~30s, where as with this change it takes ~2.5s.
Thomas Wolf [Sun, 25 Jul 2021 13:44:35 +0000 (15:44 +0200)]
[test] Create keystore with the keytool of the running JDK
Call keytool with the absolute path of "java.home". Otherwise a keytool
for a different, maybe even newer Java version might be picked up, and
then the keystore may not be readable by the JVM used to run the tests.
BatchRefUpdate: Skip saving conflicting ref names and prefixes in memory
Rather than getting all ref names and prefixes and saving them
in memory to perform the check for conflicting names, rely on
RefDirectory.isNameConflicting as it is no longer an expensive
call after it was optimized in Ie994fc.
The old optimization to save ref names and prefixes in memory
was targeted towards making clones faster. With this change,
the clone performance is unaffected when tests were done with
repos containing many(~500k) refs.
Here are few recorded elapsed times for creating 10 branches
using BatchRefUpdate on NFS based repositories with varying
loose refs count. As seen here, this change helps improve the
BatchRefUpdate performance from O(n^2) to O(1).
loose_refs_count with_change without_change
50 241 ms 310 ms
300 263 ms 1502 ms
1k 181 ms 4241 ms
2k 204 ms 6440 ms
9k 158 ms 25930 ms
20k 154 ms 60443 ms
50k 171 ms 135199 ms
110k 157 ms 329450 ms
160k 209 ms 396328 ms
This update improves the Gerrit notedb migration performance
as it uses BatchRefUpdate to write change meta refs similar to
the test performed above.
Update tests to record the number of events fired post-setup and only
assert for events fired during BatchRefUpdate.execute. For tests which
use writeLooseRef to setup refs, create new tests which assert the
number of RefsChangedEvent(s) rather than updating the existing ones
to call RefDirectory.exactRef as it changes the code path.
Avoid having to scan over ALL loose refs to determine if the
name is nested within or is a container of an existing reference.
This can get really expensive if there are too many loose refs.
Instead use exactRef and getRefsByPrefix which scan based on a
prefix.
With a simple shell script(like below) using jgit client to create
1k refs in a new repository on NFS, this change brings down the time
from 12mins to 7mins.
for ref in $(seq 1 1000); do
jgit branch "$ref"
done
Here are few recorded elapsed times to create a new branch on NFS
based repositories with varying loose refs count. As we see here,
this change improves the name conflicting check from O(n^2) to O(1).
loose_refs_count with_change without_change
50 44 ms 164 ms
300 45 ms 1193 ms
1k 38 ms 2610 ms
2k 44 ms 6003 ms
9k 46 ms 27860 ms
20k 45 ms 48591 ms
50k 51 ms 135471 ms
110k 43 ms 294252 ms
160k 52 ms 430976 ms
Petr Hrebejk [Mon, 30 Nov 2020 19:19:53 +0000 (20:19 +0100)]
Fix PackInvalidException when fetch and repack run concurrently
We are running several servers with jGit. We need to run repack from
time to time to keep the repos performant. I.e. after push we test how
many small packs are in the repo and when a threshold is reached we run
the repack.
After upgrading jGit version we've found that if someone does the clone
at the time repack is running the clone sometimes (not always) fails
because the repack removes .pack file used by the clone. Server
exception and client error attached.
I've tracked down the cause and it seems to be introduced between jGit
5.2 (which we upgraded from) and 5.3 and being caused by this commit:
Move throw of PackInvalidException outside the catch -
https://github.com/eclipse/jgit/commit/afef866a44cd65fef292c174cad445b3fb526400
The problem is that when the throw was inside of the try block the last
catch block catched the exception and called openFailed(false) method.
It is true that it called it with invalidate = false, which is wrong.
The real problem though is that with the throw outside of the try block
the openFail is not called at all and the fields activeWindows and
activeCopyRawData are not set to 0. Which affects the later called tests
like: if (++activeCopyRawData == 1 && activeWindows == 0).
The fix for this is relatively simple keeping the throw outside of the
try block and still having the invalid field set to true. I did
exhaustive testing of the change running concurrent clones and pushes
indefinitely and with the patch applied it never fails while without the
patch it takes relatively short to get the error.
Matthias Sohn [Wed, 25 Nov 2020 16:00:09 +0000 (17:00 +0100)]
Ensure that GC#deleteOrphans respects pack lock
If pack or index files are guarded by a pack lock (.keep file)
deleteOrphans() should not touch the respective files protected by the
lock file. Otherwise it may interfere with PackInserter concurrently
inserting a new pack file and its index.
The problem was caused by the following race.
All mentioned files are located in "objects/pack/".
File endings relevant in "pack" dir:
.pack
.keep
.idx
.bitmap
When ReceivePack receives a pack file it executes the following steps:
ReceivePack.service():
receivePackAndCheckConnectivity():
receivePack():
receive the pack
parse the pack, returns packLock (.keep file)
PackInserter.flush():
write tmpPck file: "insert_<random>.pack"
write tmpIdx file: "insert_<random>.idx"
real pack name: "pack-<SHA1>.pack"
real index name: "pack-<SHA1>.idx"
atomic rename tmpPack to realPack
atomic rename tmpIdx to tmpIdx
execute commands
unlock pack by removing .keep file
trigger auto gc if enabled
When PackInserter.flush() renames the temporary pack to the final
"pack-xxx.pack" file the temporary pack index file "insert_xxx.idx"
has no matching .pack file with the same base name for a short interval.
If deleteOrphans() ran during that interval it deduced the pack index
file was orphaned. Subsequently the missing pack index caused
MissingObjectExceptions since objects contained in the pack couldn't be
looked up anymore.
Bug: https://bugs.chromium.org/p/gerrit/issues/detail?id=13544
Change-Id: I559c81e4b1d7c487f92a751bd78b987d32c98719 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
David Pursehouse [Thu, 30 Jan 2020 23:38:24 +0000 (08:38 +0900)]
Fix string format parameter for invalidRefAdvertisementLine
The externalized error message added in f4fc640 ("BasePackConnection:
Check for expected length of ref advertisement", Dec 18, 2019) uses a
malformed string format. Since there is only one formatting argument,
it should be referenced with '{0}' rather than '{1}'.
Change-Id: Ibda864dfb0bb902fe07ae4bba73117b212046e8a Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Matthias Sohn [Fri, 3 Jan 2020 17:16:42 +0000 (18:16 +0100)]
WindowCache: add metric for cached bytes per repository
Since ObjectDatabase and PackFile don't know their repository use the
packfile's grand-grand-parent directory as an identifier for the
repository the packfile resides in.
Remove metric for a repository if the number of cached bytes for the
repository drops to 0 in order to ensure the map of cached bytes per
repository doesn't contain repositories which have no data cached in the
WindowCache.
Change-Id: I969ab8029db0a292e7585cbb36ca0baa797da20b Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Mon, 27 Jan 2020 22:00:57 +0000 (23:00 +0100)]
pgm daemon: fallback to user and system config if no config specified
If a config file is passed via option --config-file then use only the
options defined in that file. This helps to concisely configure the
daemon without side effects from global and system level git configs.
Otherwise fallback to user and system level configs.
Change-Id: I242de248f257579874ad0bfe4882a22502353b1f Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Fri, 13 Dec 2019 00:18:12 +0000 (01:18 +0100)]
WindowCache: add option to use strong refs to reference ByteWindows
Java GC evicts all SoftReferences when the used heap size comes close to
the maximum heap size. This means peaks in heap memory consumption can
flush the complete WindowCache which was observed to have negative
impact on performance of upload-pack in Gerrit.
Hence add a boolean option core.packedGitUseStrongRefs to allow using
strong references to reference packfile pages cached in the WindowCache.
If this option is set to true Java gc can no longer flush the
WindowCache to free memory if the used heap comes close to the maximum
heap size. On the other hand this provides more predictable performance.
Bug: 553573
Change-Id: I9de406293087ab0fa61130c8e0829775762ece8d Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Patrick Hiesel [Thu, 9 Jan 2020 09:23:12 +0000 (10:23 +0100)]
Replace usage of ArrayIndexOutOfBoundsException in treewalk
Using exceptions during normal operations - for example with the
desire of expanding an array in the failure case - can have a
severe performance impact. When exceptions are instantiated,
a stack trace is collected. Generating stack trace can be expensive.
Compared to that, checking an array for length - even if done many
times - is cheap since this is a check that can run in just a
handful of CPU cycles.
Change-Id: Ifaf10623f6a876c9faecfa44654c9296315adfcb Signed-off-by: Patrick Hiesel <hiesel@google.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Sat, 4 Jan 2020 14:44:19 +0000 (15:44 +0100)]
SshSupport#runSshCommand: don't throw exception in finally block
The CommandFailedException which was thrown in finally block is silently
discarded [1]. Refactor this method to throw the exception after the
finally block.
This fixes the warning "Null comparison always yields false: The
variable failure can only be null at this location".
Matthias Sohn [Mon, 16 Dec 2019 14:22:08 +0000 (15:22 +0100)]
Ignore warnings for generated source code in org.eclipse.jgit.benchmark
The source code in the folder .apt_generated is generated by the JMH
code generator, so there's no point in raising any warnings as this
could only be fixed in the upstream code generator.
Change-Id: I882888e7bf924f9ae74182598fcb91671a5c9818 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Sat, 30 Nov 2019 02:38:13 +0000 (03:38 +0100)]
Enhance WindowCache statistics
Add the following statistics
- cache hit count and hit ratio
- cache miss count and miss ratio
- count of successful and failed loads
- rate of failed loads
- load, eviction and request count
- average and total load time
Use LongAdder instead of AtomicLong to implement counters in order to
improve scalability.
Optionally expose these metrics via JMX, they are registered with the
platform MBean server if the config option jmx.WindowCacheStats = true
in the user or system level git config.
Bug: 553573
Change-Id: Ia2d5246ef69b9c2bd594a23934424bc5800774aa Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Sat, 3 Aug 2019 10:02:34 +0000 (12:02 +0200)]
JMH benchmark for SimpleLruCache
See [1] for JMH documentation and [2] how to use JMH in Eclipse.
The benchmarks pom currently cannot use the JGit parent pom due to an
ecj bug [3] regarding annotation processing. Hence for now do not
inherit from the JGit parent pom and copy the compiler plugin
configuration for javac from the parent pom.
After running the Maven build the benchmark can be run using Maven:
Do not rely on ArrayIndexOutOfBoundsException to detect end of input
In the Config#StringReader we relied on ArrayIndexOutOfBoundsException
to detect the end of the input. Creation of exception with (deep) stack
trace can significantly degrade performance in case when we read
thousands of config files, like in the case when Gerrit reads all
external ids from the NoteDb.
Use the buf.length to detect the end of the input.
Thomas Wolf [Thu, 12 Sep 2019 19:05:19 +0000 (21:05 +0200)]
WorkingTreeIterator: handle different timestamp resolutions
Older JGit stored only milliseconds timestamps in the index. Newer
JGit may get finer timestamps from the file system. This leads to
slow index diffs when a new JGit runs against an index produced
by older JGit because many timestamps will differ and JGit will
then do many content checks. See [1].
Handle this migration case by only comparing milliseconds if the
index entry has only millisecond precision.
The inverse may also occur; also compare only milliseconds if the
file timestamp has only millisecond precision.
Do the same also for microsecond resolution. On Windows, NTFS may
provide 100ns resolution and may be used by external programs writing
the index, but Java's WindowsFileAttributes may provide only
microseconds.
File timestamp precision in Java depends not only on the Java APIs
used by different JGit versions but may also change when running the
same Java code on different VMs. And of course the resolution may
vary among operating and file systems. Moreover, timestamp precision
in the index depends on the program that wrote the index. Canonical
git may use a different resolution, maybe even different between git
versions.
Change-Id: Idfd08606c883cb98787b2138f9baf0cc89a57b56 Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Tue, 10 Sep 2019 14:08:45 +0000 (16:08 +0200)]
Fix WorkingTreeIterator.compareMetadata() for CheckStat.MINIMAL
If CheckStat is MINIMAL or timestamps have no nanosecond part
WorkingTreeIterator.compareMetaData only checks the second part of
timestamps and ignores nanoseconds which may have ended up in the index
by using native git.
we currently proceed comparing fileLastModified and cacheLastModified
with full precision which is wrong since we determined that we detected
reduced timestamp resolution.
Fix this and also handle smudged index entries for CheckStat.MINIMAL.
Change-Id: I6149885903ac63d79b42d234cc02aa4e19578f3c Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
David Pursehouse [Wed, 10 Oct 2018 01:53:35 +0000 (10:53 +0900)]
Bazel: Require minimum bazel version 0.17.1
Check the bazel version using the checker from bazel_skylib, and
require at least version 0.17.1 which is the minimum version that
does not suffer from the Java API mismatch issue [1].
The implementation is borrowed from the Gerrit project.
Matthias Sohn [Tue, 3 Sep 2019 14:02:44 +0000 (16:02 +0200)]
Merge branch 'stable-5.0' into stable-5.1
* stable-5.0:
Prepare 4.11.10-SNAPSHOT builds
JGit v4.11.9.201909030838-r
Bazel: Update bazlets to the latest master revision
Bazel: Remove FileTreeIteratorWithTimeControl from BUILD file
BatchRefUpdate: repro racy atomic update, and fix it
Delete unused FileTreeIteratorWithTimeControl
Fix RacyGitTests#testRacyGitDetection
Change RacyGitTests to create a racy git situation in a stable way
Silence API warnings
Change-Id: I172136a031ff0730e575327cafb3527c9650a71d Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Tue, 3 Sep 2019 13:54:54 +0000 (15:54 +0200)]
Merge branch 'stable-4.11' into stable-5.0
* stable-4.11:
Prepare 4.11.10-SNAPSHOT builds
JGit v4.11.9.201909030838-r
Bazel: Update bazlets to the latest master revision
Bazel: Remove FileTreeIteratorWithTimeControl from BUILD file
BatchRefUpdate: repro racy atomic update, and fix it
Delete unused FileTreeIteratorWithTimeControl
Fix RacyGitTests#testRacyGitDetection
Change RacyGitTests to create a racy git situation in a stable way
Silence API warnings
Change-Id: Ifb6a4dbea2f48fd2ffa66eb737d61920aefedfbd Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Tue, 3 Sep 2019 12:23:29 +0000 (14:23 +0200)]
Merge branch 'stable-4.10' into stable-4.11
* stable-4.10:
Bazel: Update bazlets to the latest master revision
Bazel: Remove FileTreeIteratorWithTimeControl from BUILD file
BatchRefUpdate: repro racy atomic update, and fix it
Delete unused FileTreeIteratorWithTimeControl
Fix RacyGitTests#testRacyGitDetection
Change RacyGitTests to create a racy git situation in a stable way
Silence API warnings
Change-Id: If672b4f0c350f4e8ff7e1e706485cffd8137236d Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Matthias Sohn [Tue, 3 Sep 2019 11:24:28 +0000 (13:24 +0200)]
Merge branch 'stable-4.9' into stable-4.10
* stable-4.9:
BatchRefUpdate: repro racy atomic update, and fix it
Delete unused FileTreeIteratorWithTimeControl
Fix RacyGitTests#testRacyGitDetection
Change RacyGitTests to create a racy git situation in a stable way
Silence API warnings
Change-Id: Id5bf44645655fca40ad22bb1f1ad20a7c2e8f6db Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Han-Wen Nienhuys [Sat, 31 Aug 2019 19:33:58 +0000 (21:33 +0200)]
BatchRefUpdate: repro racy atomic update, and fix it
PackedBatchRefUpdate was creating a new packed-refs list that was
potentially unsorted. This would be papered over when the list was
read back from disk in parsePackedRef, which detects unsorted ref
lists on reading, and sorts them. However, the BatchRefUpdate also
installed the new (unsorted) list in-memory in
RefDirectory#packedRefs.
With the timestamp granularity code committed to stable-5.1, we can
more often accurately decide that the packed-refs file is clean, and
will return the erroneous unsorted data more often. Unluckily timed
delays also cause the file to be clean, hence this problem was
exacerbated under load.
The symptom is that refs added by a BatchRefUpdate would stop being
visible directly after they were added. In particular, the Gerrit
integration tests uses BatchRefUpdate in its setup for creating the
Admin group, and then tries to read it out directly afterward.
The tests recreates one failure case. A better approach would be to
revise RefList.Builder, so it detects out-of-order lists and
automatically sorts them.
Fixes https://bugs.eclipse.org/bugs/show_bug.cgi?id=548716 and
https://bugs.chromium.org/p/gerrit/issues/detail?id=11373.
Matthias Sohn [Tue, 18 Jun 2019 09:32:59 +0000 (11:32 +0200)]
Fix RacyGitTests#testRacyGitDetection
This test case assumed file system timestamp resolution of 1 second. On
filesystems with a finer resolution this test fails since the index
entry is only smudged if the file index entry's lastModified and the
lastModified of the git index itself are within the same filesystem
timer tick. Fix this by ensuring that these timestamps are identical
which should work for any filesystem timer resolution.
Bug: 548188
Change-Id: Id84d59e1cfeb48fa008f8f27f2f892c4f73985de Signed-off-by: Matthias Sohn <matthias.sohn@sap.com> Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
(cherry picked from commit 1159f9dd7c80a53c2509cd75d997a6afed37f9a6)
Matthias Sohn [Mon, 26 Aug 2019 20:43:11 +0000 (22:43 +0200)]
Return a new instance from openSystemConfig and openUserConfig
Move the handling of cached user and system config to getSystemConfig
and getUserConfig methods and revert the implementation of
openSystemConfig and openUserConfig to the old stateless
implementation.
This ensures the open methods respect the passed-in parent config, which
may be different on each invocation. Additionally, returning a new
instance matches the behavior of the previous implementation of the
default system reader, which downstream callers may be depending on.
Move the implementation of the new caching methods getSystemConfig and
getUserConfig up to SystemReader. This avoids that we break the ABI for
subclasses of SystemReader.
Also see [1] which fixed a similar problem with Gerrit's custom
SystemReader.
Matthias Sohn [Tue, 20 Aug 2019 22:29:45 +0000 (00:29 +0200)]
Avoid sign extension when comparing mtime with Instant#getEpochSecond
Ensure we use the same type when comparing seconds since the epoch.
This does not prevent that in 2038 timestamps in seconds since the epoch
stored in a 32 bit integer will overflow. Integer.MAX_VALUE translates
to 2038-01-19T03:14:07Z. After this date we'll have an issue since we
store seconds since the epoch in a 32 bit integer in some places.
Bug: 319142
Change-Id: If0c03003d40b480f044686e2f7a2f62c9f4e2fe1 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Michael Keppler [Tue, 20 Aug 2019 14:09:12 +0000 (16:09 +0200)]
Fix deprecation in DirCache caused by Instant based DirCacheEntry
Replace the two int variables smudge_s and smudge_ns by an Instant and
use the new method DirCacheEntry.mightBeRacilyClean(Instant).
Change-Id: Id70adbb0856a64909617acf65da1bae8e2ae934a Signed-off-by: Michael Keppler <Michael.Keppler@gmx.de> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
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