[JDK21] Fix jvmtiSuspendThread and jvmtiGetCarrierThread - #17999
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An unmounted virtual thread has no carrier thread. targetThread is NULL for an unmounted virtual thread. A NULL check has been added for the targetThread to prevent a segfault. Related: eclipse-openj9#17933 Signed-off-by: Babneet Singh <sbabneet@ca.ibm.com>
babsingh
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August 22, 2023 20:54
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@gacholio Requesting your review. |
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getVMThread can cause a deadlock for a virutal thread if the thread is already suspended. The suspended virtual thread halts during the mount or unmount phase while the virtualThreadInspectorCount is set to -1. Meanwhile, acquireVThreadInspector waits indefinitely for the virtualThreadInspectorCount to be set to 0 in the mount or unmount phase. To prevent the deadlock, jvmtiSuspendThread should return an error for already suspended threads without invoking getVMThread -> acquireVThreadInspector. This approach an be taken for both platform and virtual threads. Signed-off-by: Babneet Singh <sbabneet@ca.ibm.com>
gacholio
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Aug 23, 2023
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jenkins compile win jdk8 |
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jenkins test sanity zlinux jdk21 |
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Commit 1: Fix deadlock that occurs while suspending threads through JVMTI
getVMThread can cause a deadlock for a virutal thread if the thread is
already suspended. The suspended virtual thread halts during the mount
or unmount phase while the virtualThreadInspectorCount is set to -1.
Meanwhile, acquireVThreadInspector waits indefinitely for the
virtualThreadInspectorCount to be set to 0 in the mount or unmount
phase. To prevent the deadlock, jvmtiSuspendThread should return an
error for already suspended threads without invoking
getVMThread -> acquireVThreadInspector. This approach an be taken for
both platform and virtual threads.
Commit 2: Fix jvmtiGetCarrierThread
An unmounted virtual thread has no carrier thread.
targetThread is NULL for an unmounted virtual thread.
A NULL check has been added for the targetThread to prevent a segfault.
Related: #17933
Signed-off-by: Babneet Singh sbabneet@ca.ibm.com