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. ------------- Commit messages: - 8320687: sun.jvmstat.monitor.MonitoredHost.getMonitoredHost() throws unexpected exceptions when invoked concurrently Changes: https://git.openjdk.org/jdk/pull/16805/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16805&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8320687 Stats: 133 lines in 2 files changed: 116 ins; 5 del; 12 mod Patch: https://git.openjdk.org/jdk/pull/16805.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/16805/head:pull/16805 PR: https://git.openjdk.org/jdk/pull/16805
