Hi Sherman,
Nice work. It'll certainly help protect the VM from bad application
code. I've no major issues with the new code. Some comments below.
src/java.base/share/classes/java/util/zip/ZipFile.java
unused import :
import java.nio.file.Path;
line 840 : This could be marked final
private Key key;
line 914 : Same here (final)
private static HashMap<Key, Source> files = new HashMap<>();
While in this class, could you also mark inflaterCache as final (line
451)
- String prop =
sun.misc.VM.getSavedProperty("sun.zip.disableMemoryMapping");
With this property removed, I think you'll need to update
src/java.base/share/classes/sun/misc/VM.java line 278 also. It
becomes redundant code.
We'll also need to log a sub-task to track doc updates to highlight
that this property is no longer relevant.
ZipFile : line 195 :
Objects.requireNonNull(charset, "charset");
You've changed the order of exception throwing here. To aid with a
possible backport (and behaviour), could you consider moving the
check to post the 'mode' checks ? If you can't, I'll just remember it
when backporting!
line 525 :
byte[] cen = zsrc.cen;
It might be no harm to insert a comment here saying that the caller
method must check for 'ensureOpen' ?
I think you need a ensureOpen check on the new initDataOffset()
method. You could hit an NPE otherwise. E.g. :
ZipFile zf = new ZipFile(new File("/tmp/jtreg.zip"));
ZipEntry ze = zf.getEntry("jtreg/release");
InputStream is = zf.getInputStream(ze);
zf.close();
is.skip(1);
There might be room for a small improvement on the zerror method. Could
you pre-append the name of the File to each exception message via
this method ?
On the new test, are you planning to add this to the jtreg tests or
will it be
a manual stand alone ? It would have to be tuned down in terms of
resources
if added to the auto-test list.
Regards,
Sean.
On 11/11/15 20:22, Xueming Shen wrote:
Hi
Please help review the changes for JDK-8142508 (third try)
Issue: https://bugs.openjdk.java.net/browse/JDK-8142508
webrev: http://cr.openjdk.java.net/~sherman/8142508/webrev
Mainly to address the issues in current j.u.z.ZipFile implementation
as listed
below
(1) The ZIP file format support code is in native C (shared with the
VM via
ZipFile.c -> zip_util.c). Any entry lookup, creation operation
requires multiple
round-trips of expensive jni calls.
(2) The native C implementation which uses mmap to map in the
central directory
table appears to be a big risk of vm crash when the underlying
jar file gets
overwritten with new contents while it is still being used by
other ZipFile. The
crash reports keep coming in even after we have introduced in
system flag
to disable it (sun.zip.disableMemoryMapping).
(3) The use of "filename + lastModified()" cache (zip_util.c)
appears to be broken
if the timestamp is in low resolution/precision
(File.getModified() for example,
might only have "second" ersolution on solaris/linux), and/or
the file is being
overwritten.
The clean solution appears to bring the ZIP format support code
completely from
native to Java to remove the jni invocation cost and the mmap risk.
Also to use
the fileKey and lastModified from
java.nio.file.attribute.BasicFileAttributes to have
better/correct cache matching.
Benchmark:
This simple jmh measurement suggests a big boost of the performance of
ZipFile.getEntry()/entries()/getStream() which are basically entry
related
accesses (the "open only" has some regression, which is expected as we
switched from the mmap to simply read the cen table in into a byte[])
http://cr.openjdk.java.net/~sherman/8142508/MyBenchmark.java
# JDK9 base
Benchmark Mode Cnt Score Error Units
MyBenchmark.testEntries avgt 50 13.671 ± 0.385 ms/op
MyBenchmark.testGetEntry avgt 50 17.414 ± 0.803 ms/op
MyBenchmark.testGetStream avgt 50 42.398 ± 10.136 ms/op
MyBenchmark.testOpen avgt 50 3.049 ± 0.094 ms/op
MyBenchmark.testRead avgt 50 215.179 ± 9.926 ms/op
MyBenchmark.testReadAll avgt 50 244.422 ± 19.375 ms/op
--------------------------------------------------------------------------------------
# JDK9 ZipFile without jni invocation
Benchmark Mode Cnt Score Error Units
MyBenchmark.testEntries avgt 50 6.436 ± 0.422 ms/op
MyBenchmark.testGetEntry avgt 50 10.021 ± 0.699 ms/op
MyBenchmark.testGetStream avgt 50 38.713 ± 16.687 ms/op
MyBenchmark.testOpen avgt 50 3.288 ± 0.119 ms/op
MyBenchmark.testRead avgt 50 220.653 ± 8.529 ms/op
MyBenchmark.testReadAll avgt 50 249.798 ± 18.438 ms/op
---------------------------------------------------------------------------------------
Test:
http://cr.openjdk.java.net/~sherman/8142508/webrev/test/java/util/zip/ZipFile/TestZipFile.java.html
Verified the new ZipFile runs as expected when the underlying
jar/zip file get
deleted/overwritten when the zip still be used. The "old" ZipFile
fails to continue
to work but no crash, and the "new" one works correctly on updated
zip file
without problem (The test runs a little long, have not decided if it
should be
checked in as unit test).
-Sherman
