RFR: 8262386: resourcehogs/serviceability/sa/TestHeapDumpForLargeArray.java timed out

[Lin Zang]

8262386: resourcehogs/serviceability/sa/TestHeapDumpForLargeArray.java timed out

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Commit messages:
 - code refine
 - 8262386: resourcehogs/serviceability/sa/TestHeapDumpForLargeArray.java timed out

Changes: https://git.openjdk.java.net/jdk/pull/2803/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2803&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262386
  Stats: 86 lines in 2 files changed: 59 ins; 5 del; 22 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2803.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2803/head:pull/2803

PR: https://git.openjdk.java.net/jdk/pull/2803