[OpenJDK 2D-Dev] JVM crash in libc pre JDK7

[Ben Cheng]

Not sure this is the right place to ask this question, but I am going to
give it a try.

We are seeing some JVM crashes in libc malloc()/free() invoked from
libdcpr.so with Java 6. After browsing the bug database there are a few
similar ones as described in 6510993 and 6645511. I used the SwingSet2
example from 6510993 as the benchmark and I usually can reproduce the crash
within a couple hours, but for some reason the crash is simply not
reproducible with openjdk7.

With server VM build 1.6.0-b105 the stack trace in the core file looks like
the following:


#0  0xffffe410 in __kernel_vsyscall ()
#1  0x4bdce9a1 in raise () from /lib/tls/i686/cmov/libc.so.6
#2  0x4bdd02b9 in abort () from /lib/tls/i686/cmov/libc.so.6
#3  0x0643b36b in os::abort ()
   from /auto/buildtools/java/jdk1.6.0/jre/lib/i386/server/libjvm.so
#4  0x0651c431 in VMError::report_and_die ()
   from /auto/buildtools/java/jdk1.6.0/jre/lib/i386/server/libjvm.so
#5  0x0643f7a0 in JVM_handle_linux_signal ()
   from /auto/buildtools/java/jdk1.6.0/jre/lib/i386/server/libjvm.so
#6  0x0643d058 in signalHandler ()
   from /auto/buildtools/java/jdk1.6.0/jre/lib/i386/server/libjvm.so
#7  <signal handler called>
#8  0x4be0863b in malloc_consolidate () from /lib/tls/i686/cmov/libc.so.6
#9  0x4be09653 in _int_malloc () from /lib/tls/i686/cmov/libc.so.6
#10 0x4be0b411 in malloc () from /lib/tls/i686/cmov/libc.so.6
#11 0xb263a1c5 in doeMem_malloc ()
   from /auto/buildtools/java/jdk1.6.0/jre/lib/i386/libdcpr.so
#12 0xb2643c61 in setOutputArea ()
   from /auto/buildtools/java/jdk1.6.0/jre/lib/i386/libdcpr.so
#13 0xb263cdf4 in Java_sun_dc_pr_PathFiller_setOutputArea ()
   from /auto/buildtools/java/jdk1.6.0/jre/lib/i386/libdcpr.so

I checked the openjdk7 code structure and found that heavy redesign seems
happening under sun/dc, as everything below pr is simply gone. That makes me
believe that whatever the problem is on Java 6 it is likely to be related to
the implementation under pr.

Here comes my main question: for people who rewrite sun/dc for openjdk7, do
you happen to know any patch to workaround the crashes in Java 6? We are
happy to try any patch to eliminate the annoying JVM crashes.

Thanks,
-Ben
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