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<p class="MsoPlainText">By the way, the link of the patch that caused problems was
<a href="https://bugs.openjdk.java.net/browse/JDK-8217432">https://bugs.openjdk.java.net/browse/JDK-8217432</a>.<o:p></o:p></p>
<p class="MsoPlainText">The test would fail with 32-bit jdk even on 64-bit platforms.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">> Hi,<o:p></o:p></p>
<p class="MsoPlainText">> <o:p></o:p></p>
<p class="MsoPlainText">> After this patch was applied (since jdk8u212 and jdk-11.0.3, to be specific), we started to get test failures with jtreg.<o:p></o:p></p>
<p class="MsoPlainText">> The failed test case was jdk8u/hotspot/test/gc/metaspace/TestCapacityUntilGCWrapAround.java.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> It always fails on windows-32bit platform, and fails on linux-32bit if -XX:MaxMetaspaceSize is set.<o:p></o:p></p>
<p class="MsoPlainText">> <o:p></o:p></p>
<p class="MsoPlainText">> The failure message was:<o:p></o:p></p>
<p class="MsoPlainText">> java.lang.IllegalStateException: WB_IncMetaspaceCapacityUntilGC: could not increase capacity until GC due to contention with another thread<o:p></o:p></p>
<p class="MsoPlainText">> at sun.hotspot.WhiteBox.incMetaspaceCapacityUntilGC(Native Method)<o:p></o:p></p>
<p class="MsoPlainText">> at TestCapacityUntilGCWrapAround.main(TestCapacityUntilGCWrapAround.java:51)<o:p></o:p></p>
<p class="MsoPlainText">> <o:p></o:p></p>
<p class="MsoPlainText">> I checked the code, and found that MetaspaceGC::inc_capacity_until_GC was passed a value of 4G-page_size-1,<o:p></o:p></p>
<p class="MsoPlainText">> which caused addition overflow when computing new_value, and new_value always set to "align_size_down(max_uintx, Metaspace::commit_alignment())".<o:p></o:p></p>
<p class="MsoPlainText">> So when MaxMetaspaceSize defaults to or is set to a value less than it, the function will return false to WB_IncMetaspaceCapacityUntilGC,<o:p></o:p></p>
<p class="MsoPlainText">> which will then throw an Exception, causing the test failure.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> On win-32 platform, the default value of MaxMetaspaceSize is 4G - allocation_granularity,<o:p></o:p></p>
<p class="MsoPlainText">> which is 4G - 64K (according to <a href="https://devblogs.microsoft.com/oldnewthing/20031008-00/?p=42223">
https://devblogs.microsoft.com/oldnewthing/20031008-00/?p=42223</a>),<o:p></o:p></p>
<p class="MsoPlainText">> this is very likely to be less than "new_value" and cause test failure.<o:p></o:p></p>
<p class="MsoPlainText">><o:p> </o:p></p>
<p class="MsoPlainText">> Do you have any idea how to fix this?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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