Segfault when running GenCopy with Dacapo callbacks

[qinsoon]

I ran into this problem when trying to debug #54.

I was using ef24f49 with dacapo callbacks but no probe.

MMTK_PLAN=GenCopy build/linux-x86_64-normal-server-slowdebug/jdk/bin/java -XX:+UseThirdPartyHeap -Xms128M -Xmx128M -Djava.library.path=/home/yilin/Code/ci-perf-kit/probes/rust_mmtk -cp /home/yilin/Code/ci-perf-kit/probes/probes.jar:/home/yilin/Code/ci-perf-kit/probes/rust_mmtk/java:/usr/share/benchmarks/dacapo/dacapo-9.12-bach.jar Harness -n 2 -c probe.DacapoBachCallback fop

I have encountered different errors, such as

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007f41b8a40fe1, pid=1573, tid=1604
#
# JRE version: OpenJDK Runtime Environment (11.0) (slowdebug build 11-internal+0-adhoc.yilin.openjdk)
# Java VM: OpenJDK 64-Bit Server VM (slowdebug 11-internal+0-adhoc.yilin.openjdk, mixed mode, tiered, third-party gc, linux-amd64)
# Problematic frame:
# V  [libjvm.so+0x75bfe1]  oopDesc::size_given_klass(Klass*)+0x51
#
# Core dump will be written. Default location: Core dumps may be processed with "/usr/share/apport/apport %p %s %c %d %P %E" (or dumping to /home/yilin/Code/mmtk-openjdk/repos/openjdk/core.1573)
#
# An error report file with more information is saved as:
# /home/yilin/Code/mmtk-openjdk/repos/openjdk/hs_err_pid1573.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
#

or

thread '<unnamed>' panicked at 'Invalid klass-id: 4f for oop: 40000340000', src/object_scanning.rs:132:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal runtime error: failed to initiate panic, error 5
Aborted (core dumped)

or

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007f7cf071b574, pid=2192, tid=2205
#
# JRE version: OpenJDK Runtime Environment (11.0) (slowdebug build 11-internal+0-adhoc.yilin.openjdk)
# Java VM: OpenJDK 64-Bit Server VM (slowdebug 11-internal+0-adhoc.yilin.openjdk, mixed mode, tiered, third-party gc, linux-amd64)
# Problematic frame:
# V  [libjvm.so+0x320574]  Klass::layout_helper() const+0xc
#
# Core dump will be written. Default location: Core dumps may be processed with "/usr/share/apport/apport %p %s %c %d %P %E" (or dumping to /home/yilin/Code/mmtk-openjdk/repos/openjdk/core.2192)
#
# An error report file with more information is saved as:
# /home/yilin/Code/mmtk-openjdk/repos/openjdk/hs_err_pid2192.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
#

It worked fine if we did not do warmup runs.

MMTK_PLAN=GenCopy build/linux-x86_64-normal-server-slowdebug/jdk/bin/java -XX:+UseThirdPartyHeap -Xms128M -Xmx128M -Djava.library.path=/home/yilin/Code/ci-perf-kit/probes/rust_mmtk -cp /home/yilin/Code/ci-perf-kit/probes/probes.jar:/home/yilin/Code/ci-perf-kit/probes/rust_mmtk/java:/usr/share/benchmarks/dacapo/dacapo-9.12-bach.jar Harness -c probe.DacapoBachCallback fop