Seen once:
[----------] 2 tests from SymbolTable (3 ms total)

# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/scratch/mesos/slaves/c29d9578-9608-44e5-8e00-6c504a81f8a3-S5/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/d0d61978-b700-473e-900e-651cf5325510/runs/b21dba59-db6e-44d7-9102-cd8977d0f0b9/workspace/open/src/hotspot/os/bsd/semaphore_bsd.cpp:56), pid=75574, tid=24835
# assert(ret == 0) failed: Failed to signal semaphore
#
# JRE version: Java(TM) SE Runtime Environment (12.0) (fastdebug build 12-internal+0-2018-08-14-1753302.gerard.ziemski.jdk12)
[----------] 1 test from SynchronizerTest
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 12-internal+0-2018-08-14-1753302.gerard.ziemski.jdk12, mixed mode, tiered, compressed oops, g1 gc, bsd-amd64)
# Core dump will be written. Default location: /cores/core.75574