OpenJDK 11.0.9 crashed on a heavy-load server.

ADDITIONAL SYSTEM INFORMATION :
OS and version: Ubuntu 16.04.6 LTS
CPU model: Intel(R) Xeon(R) CPU E5-4610 v4 @ 1.80GHz
Number of CPU cores: 4CPUs, each has 10 cores
Size of physical memory: 16384 MB * 20

A DESCRIPTION OF THE PROBLEM :
We made some changes to a class file in the JUnit project, and let several JVMs execute the corresponding JUnit test. We found that OpenJDK 11.0.9 crashed while executing on our heavy-load server.
The crash log is on: https://drive.google.com/file/d/1Ci8X6T6FP-c_KwlDziUDyfZ6Ot4X5jjT/view?usp=sharing

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
When the server is executing lots of tasks:
Download the zip file: https://drive.google.com/file/d/14rssCVHnLJv2wACwvqABNNMivGnYpv1q/view?usp=sharing
unzip it and cd into it
run command: java -cp sootOutput/junit-jython/:hamcrest-all-1.3.jar:junit-4.12.jar org.junit.runner.JUnitCore org.python.core.PyArrayTest

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No crash
ACTUAL -
Crash