Integrated: 8320687: sun.jvmstat.monitor.MonitoredHost.getMonitoredHost() throws unexpected exceptions when invoked concurrently

[Jaikiran Pai]

On Fri, 24 Nov 2023 06:06:16 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

> Can I please get a review of this change which proposes to fix the issue noted in https://bugs.openjdk.org/browse/JDK-8320687?
> 
> As noted in the issue, the `sun.jvmstat.monitor.MonitoredHost.getMonitoredHost()` uses a shared instance of `java.util.ServiceLoader` to load `MonitoredHostService` services. The `ServiceLoader` class javadoc explicitly notes that it isn't thread safe. The issue at hand is caused to due using an instance of `ServiceLoader` concurrently by multiple threads.
> 
> The fix proposes to guard the usage of the shared `ServiceLoader` instance through the `monitoredHosts` object monitor. We already use that monitor when dealing with the internal cache which is populated after loading the relevant `MonitoredHostService`(s).
> 
> A new jtreg test has been introduced which always reproduces the issue without the source changes and passes with this fix.
> 
> tier1, tier2, tier3 and svc_tools tests have been run with this change and all passed.

This pull request has now been integrated.

Changeset: 81484d8c
Author:    Jaikiran Pai <jpai at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/81484d8c0520cf55ec58fc7b4c81880e69537674
Stats:     103 lines in 2 files changed: 93 ins; 7 del; 3 mod

8320687: sun.jvmstat.monitor.MonitoredHost.getMonitoredHost() throws unexpected exceptions when invoked concurrently

Reviewed-by: alanb, kevinw

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PR: https://git.openjdk.org/jdk/pull/16805