Don't use VM.maxDirectMemory() on IBM J9 / Eclipse OpenJ9 to retrieve direct memory limit (#7966)

Motivation:

On J9 / OpenJ9 netty initializes this value with 64M, even the direct accessible memory is actually unbounded.

Modifications:

Skip usage of VM.maxDirectMemory() on J9 / OpenJ9

Result:

More correct direct memory limit detection. Fixes #7654.
This commit is contained in:
Norman Maurer 2018-05-25 14:35:32 +02:00 committed by GitHub
parent c3637ff42c
commit 8a85761500
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@ -993,10 +993,14 @@ public final class PlatformDependent {
try {
systemClassLoader = getSystemClassLoader();
// On z/OS we should not use VM.maxDirectMemory() as it not reflects the correct value.
// When using IBM J9 / Eclipse OpenJ9 we should not use VM.maxDirectMemory() as it not reflects the
// correct value.
// See:
// - https://github.com/netty/netty/issues/7654
if (!SystemPropertyUtil.get("os.name", "").toLowerCase().contains("z/os")) {
String vmName = SystemPropertyUtil.get("java.vm.name", "").toLowerCase();
if (!vmName.startsWith("ibm j9") &&
// https://github.com/eclipse/openj9/blob/openj9-0.8.0/runtime/include/vendor_version.h#L53
!vmName.startsWith("eclipse openj9")) {
// Try to get from sun.misc.VM.maxDirectMemory() which should be most accurate.
Class<?> vmClass = Class.forName("sun.misc.VM", true, systemClassLoader);
Method m = vmClass.getDeclaredMethod("maxDirectMemory");