> This PR adds ranked monitor support to the debug agent. The debug agent has a > large number of monitors, and it's really hard to know which order to grab > them in, and for that matter which monitors might already be held at any > given moment. By imposing a rank on each monitor, we can check to make sure > they are always grabbed in the order of their rank. Having this in place when > I was working on [JDK-8324868](https://bugs.openjdk.org/browse/JDK-8324868) > would have made it much easier to detect a deadlock that was occuring, and > the reason for it. That's what motivated me to do this work > > There were 2 or 3 minor rank issues discovered as a result of these changes. > I also learned a lot about some of the more ugly details of the locking > support in the process. > > Tested with the following on all supported platforms and with virtual threads: > > com/sun/jdi > vmTestbase/nsk/jdi > vmTestbase/nsk/jdb > vmTestbase/nsk/jdwp > > Still need to run tier2 and tier5. > > Details of the changes follow in the first comment.
Chris Plummer has updated the pull request incrementally with one additional commit since the last revision: Call verifyMonitorRank() when doing a wait since wait does an exit and enter, so we should do the same rank check that we do during an enter. ------------- Changes: - all: https://git.openjdk.org/jdk/pull/19044/files - new: https://git.openjdk.org/jdk/pull/19044/files/ece5f34f..c782279b Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=19044&range=02 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19044&range=01-02 Stats: 22 lines in 1 file changed: 15 ins; 2 del; 5 mod Patch: https://git.openjdk.org/jdk/pull/19044.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/19044/head:pull/19044 PR: https://git.openjdk.org/jdk/pull/19044
