Zbynek Vyskovsky created COMPRESS-388:
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Summary: Improve concurrent reads from ZipFile
Key: COMPRESS-388
URL: https://issues.apache.org/jira/browse/COMPRESS-388
Project: Commons Compress
Issue Type: Improvement
Components: Archivers
Affects Versions: 1.13
Environment: Any
Reporter: Zbynek Vyskovsky
Fix For: 1.14
Concurrent reads on the ZipFile archive is terribly slow on multiprocessor
systems. On my 4 CPU laptop it shows 26 reads/s vs 2 reads/s on 100MB samples
for example.
The cause is the use of synchronized blocks to access the underlying file
channel. This may be required for generic SeekableByteChannel but most commonly
there is FileChannel implementation which supports lock-free reading from any
position (i.e. using pread/pwrite system calls or their equivalent).
With the fix the performance is about 10 times faster (on 4 CPU system, with
more processor the difference should grow significantly).
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