Test appears to pass fine with G1. But it fails with other GCs, for example
Parallel, Shenandoah, etc, it fails:
$ CONF=linux-x86_64-server-fastdebug make test
TEST=java/io/ObjectStreamClass/ObjectStreamClassCaching.java
TEST_VM_OPTS="-XX:+UseParallelGC"
test ObjectStreamClassCaching.testCacheReleaseUnderMemoryPressure(): success
test ObjectStreamClassCaching.testCachingEffectiveness(): failure
java.lang.AssertionError: Cache lost entry although memory was not under
pressure expected [false] but found [true]
at org.testng.Assert.fail(Assert.java:99)
at org.testng.Assert.failNotEquals(Assert.java:1037)
at org.testng.Assert.assertFalse(Assert.java:67)
I believe this is because `System.gc()` is not that reliable about what happens
with weak references. As seen with other GCs, they can clear the weakrefs on
Full GC. In fact, the test fails with G1 if we do a second System.gc() in this
test. So the test itself is flaky. The fix is to avoid doing `System.gc()`
altogether in that subtest. The test is still retained to see that reference is
not cleared for a while.
Additional testing:
- [x] Linux x86_64 fastdebug, affected test with `-XX:+UseSerialGC`, 100
repetitions
- [x] Linux x86_64 fastdebug, affected test with `-XX:+UseParallelGC`, 100
repetitions
- [x] Linux x86_64 fastdebug, affected test with `-XX:+UseG1GC`, 100
repetitions
- [x] Linux x86_64 fastdebug, affected test with `-XX:+UseShenandoahGC`, 100
repetitions
- [x] Linux x86_64 fastdebug, affected test with `-XX:+UseZGC`, 100 repetitions
-------------
Commit messages:
- Fix
Changes: https://git.openjdk.org/jdk/pull/9533/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9533&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8283276
Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
Patch: https://git.openjdk.org/jdk/pull/9533.diff
Fetch: git fetch https://git.openjdk.org/jdk pull/9533/head:pull/9533
PR: https://git.openjdk.org/jdk/pull/9533
