-Djdk.tracePinnedThreads

[Cay Horstmann]

I re-read the section on the jdk.tracePinnedThreads sysprop in
https://openjdk.java.net/jeps/425:

"The system property jdk.tracePinnedThreads triggers a stack trace when 
a thread blocks while pinned."

I interpreted this to expect a stack trace whenever a thread blocks 
while pinned.

Since that's not been my experience, I ran a simple program that spawned 
ten virtual threads, each acquiring the same monitor. With 
-Djdk.tracePinnedThreads=full, I got one stack trace and not ten. Of 
course, one is enough, so I guessed this is by design. And then I 
discovered java.lang.PinnedThreadPrinter.

It might be good to clarify the JEP. "Recently seen duplicates are not 
printed."

Cheers,

Cay

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Cay S. Horstmann | http://horstmann.com | mailto:cay at horstmann.com