RFR: JDK-8002152: javadoc could write out files on a worker thread

[Pavel Rappo]

On Mon, 22 Feb 2021 17:56:25 GMT, Jonathan Gibbons <jjg at openjdk.org> wrote:

> there is very little change in the utilization of the background writer as a function of the question size

Did you mean "queue size"? If so, then I also noticed that in my observation no. 2 under the results table here: https://github.com/openjdk/jdk/pull/2665#issuecomment-783503529 For me, utilization roughly stayed at the same 20% mark regardless of the number of queued tasks.

To me, this indicates conflicting readings. On the one hand, we have 20% of "utilization". On the other hand, 1/4 of attempts to acquire a permit to hand over a task to the executor fail. Put differently, in 1/4 of the cases the producer waits for the consumer who works at 20% capacity. Why?

I think we should use suitable tools (e.g. profilers) and/or ask experts in performance. If nothing else, this will help us diagnose such issues in the future.

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PR: https://git.openjdk.java.net/jdk/pull/2665