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>
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>
The benchmark module currently has no parent, adjust the version used
here to the one used by all the other jgit Maven modules.
Change-Id: I8807a694fe23f8f131d1d22a58a3e18874d756cc
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
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>
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>
The benchmarks can be built and run using bazel by running:
$ bazel run //org.eclipse.jgit.benchmarks:benchmarks
Change-Id: I6679750eaa0f2be30ed9d45036e013b0ea4fcc86
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Results on Mac OS 10.14.6 using APFS:
Result "org.eclipse.jgit.benchmarks.LookupFileStoreBenchmark.testLookupFileStore":
44583.277 ±(99.9%) 2666.096 ns/op [Average]
(min, avg, max) = (43707.073, 44583.277, 45320.685), stdev = 692.377
CI (99.9%): [41917.181, 47249.373] (assumes normal distribution)
Secondary result
"org.eclipse.jgit.benchmarks.LookupFileStoreBenchmark.testLookupFileStore:·stack":
Stack profiler:
....[Thread state
distributions]........................................................
100.0% RUNNABLE
....[Thread state:
RUNNABLE].............................................................
42.5% 42.5% sun.nio.fs.UnixNativeDispatcher.realpath0
37.9% 37.9% sun.nio.fs.UnixNativeDispatcher.stat0
11.0% 11.0% sun.nio.fs.BsdNativeDispatcher.getfsstat
7.6% 7.6% sun.nio.fs.BsdNativeDispatcher.fsstatEntry
0.7% 0.7% sun.nio.fs.BsdNativeDispatcher.endfsstat
0.1% 0.1% sun.nio.fs.UnixPath.initOffsets
0.0% 0.0% sun.nio.fs.UnixFileAttributes.get
0.0% 0.0% java.util.zip.Inflater.inflateBytes
0.0% 0.0% sun.misc.Unsafe.compareAndSwapInt
0.0% 0.0% sun.nio.fs.BsdFileStore.findMountEntry
This shows that FS.attrCacheByPath should be useful to reduce overhead
of looking up the FileStore of a given file.
Change-Id: I7213086b42e0453f0ee149660d507dac2a4644cc
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
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:
$ java -jar org.eclipse.jgit.benchmarks/target/benchmarks.jar
or in Eclipse by running the main method of the SimpleLruCacheBenchmark
class.
[1] https://openjdk.java.net/projects/code-tools/jmh/
[2] http://alblue.bandlem.com/Page/3/index.html
[3] https://eclip.se/532029
CQ: 20517
CQ: 20518
Change-Id: Idca8a9e0980f0b8a9c741c4c9e97d03c62f07c8d
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
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.
Change-Id: I12266f25751373a870ce3fa623cf2a95d882d521
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.
[1] https://www.eclipse.org/forums/index.php/t/1100344/
Change-Id: Idfd08606c883cb98787b2138f9baf0cc89a57b56
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
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.
If
fileLastModified.getEpochSecond() == cacheLastModified.getEpochSecond()
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>
Using buildifier from master branch and the command:
$ buildifier -r -lint fix -warnings all .
Change-Id: I19c8ff183081093cb73bed7221a78a91b6cba4dc
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
Bazelisk is utility to switch to the right Bazel version, that we
used to have with Buck build tool: [1].
Bazelisk will download the right Bazel version only once and will use
it in subsequent calls:
$ bazelisk build :release
2019/06/06 16:22:15 Downloading \
https://releases.bazel.build/0.26.1/release/bazel-0.26.1-linux-x86_64...
Bazelisk is storing the binaries in user's cache directory: [2], e.g.
on Linux OS:
$ ls -1 ~/.cache/bazelisk/bin
bazel-0.26.1-linux-x86_64
* [1] https://github.com/bazelbuild/bazelisk
* [2] https://golang.org/pkg/os/#UserCacheDir
Change-Id: Ia9180fb75f8cc17a0a0232622cf33a13bfad6b60
Signed-off-by: David Ostrovsky <david@ostrovsky.org>
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.
[1] https://github.com/bazelbuild/bazel/issues/6027
Change-Id: I224250088a1f5072fcaa3ec81228f4d2cb8cb389
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>
* 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>
* 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>
* 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>
* 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>
Matthias Sohn
Patrick Hiesel
David Pursehouse
Saša Živkov
Thomas Wolf
David Ostrovsky