RFR: 8256435: [TESTBUG] java/foreign/TestHandshake.java fails with direct buffer memory OOM

[Nick Gasson]

I ran this test on a machine with 224 logical CPUs and it fails with:

  ITERATION 3
  test TestHandshake.testHandshake("SegmentMismatchAccessor", TestHandshake$$Lambda$57/0x00000001000e7968 at 37c4b344): failure
  java.lang.OutOfMemoryError: Cannot reserve 1000000 bytes of direct buffer memory (allocated: 536008192, limit: 536870912)

SegmentMismatchAccessor allocates a 1MB native segment for each CPU on
each iteration. This can quickly reach the allocation limit if there is
no intervening GC. Explicitly close the segment after each iteration to
release the memory.

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Commit messages:
 - 8256435: [TESTBUG] java/foreign/TestHandshake.java fails with direct buffer memory OOM

Changes: https://git.openjdk.java.net/jdk/pull/1254/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1254&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256435
  Stats: 9 lines in 1 file changed: 8 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1254.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1254/head:pull/1254

PR: https://git.openjdk.java.net/jdk/pull/1254