RFR: 8309305: sun/security/ssl/SSLSocketImpl/BlockedAsyncClose.java fails with jtreg test timeout

[Andrey Turbanov]

On Thu, 8 Jun 2023 14:25:26 GMT, Matthew Donovan <mdonovan at openjdk.org> wrote:

> This PR improves the reliability of the BlockedAsyncClose test by addressing an edge case/race condition between the two test threads. The purpose of the test is to verify that an SSLSocket can be closed if a thread is blocked in a write operation. 
> 
> The test starts a "write" thread that writes data to a socket until the output buffer was filled, causing the write operation to block. The main thread then calls `SSLSocket.close()`. The original code used `Thread.sleep(1000)` to wait for the write-thread to block. However, 1 second isn't always long enough and if the write-thread isn't blocked and the output buffer is full (or almost full), the `socket.close()` call may block when it tries to send the close_notify alert. This is the condition that caused this bug.
> 
> My change uses a Lock to determine if the write thread is blocked. In the write thread, the lock creates a critical section around the `write()` call. The main thread uses `tryLock()` with a timeout to determine that the write() call is taking too long and thus likely blocked. 
> 
> While there, I also updated the test to use the SSLContextTemplate class.

test/jdk/sun/security/ssl/SSLSocketImpl/BlockedAsyncClose.java line 90:

> 88:         // if the writeLock is not released by the other thread within 10
> 89:         // seconds it is probably blocked, and we can try to close the socket
> 90:         while(writeLock.tryLock(10, TimeUnit.SECONDS)) {

Suggestion:

        while (writeLock.tryLock(10, TimeUnit.SECONDS)) {

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PR Review Comment: https://git.openjdk.org/jdk/pull/14378#discussion_r1228181139