RFR: 8272600: (test) Use native "sleep" in Basic.java

[Roger Riggs]

On Tue, 24 Aug 2021 16:16:45 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> The intermittent test in java/lang/ProcessBuilder/Basic.java has identified unexpected messages from a child Java VM
>> as the cause of the test failure.  Attempts to control the output of the child VM have failed, the VM is unrepentant .
>> 
>> There is no functionality in the child except to wait long enough for the test to finish and the child is destroyed.
>> The fix is to switch from using a Java child to using a native child; a new executable `sleepmillis`.
>
> test/jdk/java/lang/ProcessBuilder/Basic.java line 2635:
> 
>> 2633:         List<String> childArgs = null;
>> 2634:         Path sleepExe = TEST_NATIVEPATH.resolve("sleepmillis");
>> 2635:         if (sleepExe.toFile().canExecute()) {
> 
> Why is the fallback necessary? Other test cases such as test/jdk/tools/launcher/JliLaunchTest.java do not have such a fallback.
> 
> Also, I noticed that JliLaunchTest does something like this:
> 
> 
>         Path launcher = Paths.get(System.getProperty("test.nativepath"),
>             "JliLaunchTest" + (Platform.isWindows() ? ".exe" : ""));
> 
> 
> but test/jdk/java/lang/reflect/exeCallerAccessTest/CallerAccessTest.java doesn't add ".exe", so it may not be necessary.

See above, the java Child is more portable and lower maintenance.
Windows looks for xxx.exe if xxx is not found.

> test/jdk/java/lang/ProcessBuilder/exeSleepMillis.c line 45:
> 
>> 43:     sleeptime.tv_nsec = (millis % 1000) * 1000 * 1000;
>> 44:     int rc;
>> 45:     while ((rc = nanosleep(&sleeptime, &sleeptime)) > 0) {
> 
> is `nanosleep` a portable call? I couldn't find documentation for it with google search of `nanosleep site:docs.microsoft.com`.

Sadly, true.
Falling back to the portable 'sleep(seconds)' is necessary; but the timing will be less precise.
C++ supports a higher resolution 'sleep_for' but the JDK native test build does not support building
main programs using C++ and its not worth the complications added.

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PR: https://git.openjdk.java.net/jdk/pull/5239