Every 1-2 months we run into into such kind of failures on AIX:

[2.498s][warning][os,thread] Failed to start thread "Unknown thread" - pthread_create failed (11=EAGAIN) for attributes: stacksize: 2112k, guardsize: 0k, detached.
[2.498s][warning][os,thread] Number of threads approx. running in the VM: 4223
[2.498s][warning][os,thread] Checking JVM parameter MaxExpectedDataSegmentSize (currently 8388608k) might be helpful
[2.498s][warning][os,thread] Failed to start the native thread for java.lang.Thread "Thread-4213"

[error occurred during error reporting (), id 0xe0000000, Internal Error (/workspace/openjdk-jdk-dev-aix_ppc64-dbg/jdk/src/hotspot/os/aix/os_aix.cpp:2971)]
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (malloc) failed to allocate 56 bytes. Error detail: AllocateHeap
[thread 3856 also had an error]
# An error report file with more information is saved as:
# /tmp/hs_err_pid13959464.log
[thread 76331 also had an error]