如何修复：java.lang.OutOfMemoryError：请求的数组大小超过 VM 限制，同时为项目运行 Junit

Question

Getting below exception while running Junit , Not sure which part of code leading to this issue: (using ANT - 1.9.4, ANT_OPTS=-Xmx10G) ( )

Tests run: 544, Failures: 1, Errors: 0, Time elapsed: 10,258.816 sec

   [junit] Exception in thread "main" java.lang.OutOfMemoryError: Requested array size exceeds VM limit
   [junit]  at java.lang.StringCoding$StringEncoder.encode(StringCoding.java:300)
   [junit]  at java.lang.StringCoding.encode(StringCoding.java:344)
   [junit]  at java.lang.StringCoding.encode(StringCoding.java:387)
   [junit]  at java.lang.String.getBytes(String.java:958)
   [junit]  at org.apache.tools.ant.taskdefs.optional.junit.PlainJUnitResultFormatter.endTestSuite(PlainJUnitResultFormatter.java:152)
   [junit]  at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.fireEndTestSuite(JUnitTestRunner.java:619)
   [junit]  at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.run(JUnitTestRunner.java:452)
   [junit]  at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.launch(JUnitTestRunner.java:911)
   [junit]  at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.main(JUnitTestRunner.java:768)

The exception is thrown after the tests are run and test report generation starts.

This is how junit is configured:

<junit fork="yes" newenvironment="false" haltonfailure="no" failureproperty="junit.failure" printsummary="yes" maxmemory="10096m">

Answer 1

Are you sure you are using ANT 1.9.4?

Your stacktrace matches the source code of PlainJUnitResultFormatter in ANT version 1.8.4:

out.write(sb.toString().getBytes());

Whereas in the source code of PlainJUnitResultFormatter in ANT version 1.9.4:

write(StringUtils.LINE_SEP);

there is no call of String.getBytes() where the exception occurs.

The reason to ask is this comment from the ANT 1.9.4 release notes :

• changes to JUnitTestRunner and PlainJUnitResultFormatter to make OutOfMemoryErrors less likely. Bugzilla Report 45536

So the solution would be to upgrade to ANT 1.9.4 or later