Here's a new webrev:
http://cr.openjdk.java.net/~cjplummer/8228625/webrev.01/
I decided to add a 2 second delay to make sure the test always passes
and avoids the issues in JDK-8230872. After some internal discussion
there seems to be some consensus that SA is probably not very stable
when attaching to an active process, and I'd rather not have those
issues disrupting this test. I filed a CR to write a new test without
the 2 second delay so we can still reproduce these issues. See:
https://bugs.openjdk.java.net/browse/JDK-8231288
Besides now using ProcessTools.startProcess() with a line predicate
instead of Runtime.exec(), I also did a bit of cleaning up of variable
names and added a few more diagnostic printlns.
thanks,
Chris
On 9/19/19 2:40 PM, Chris Plummer wrote:
One thing I didn't mention before is that using "jshell> " as the line
predicate does not work because jshell does not produce a \n after
generating this prompt, thus it's not actually a line and no attempt
will be made to match it, so eventually it times out. I fixed this by
using a snippet from one of the previous 2 lines"
Welcome to JShell -- Version 14-internal
For an introduction type: /help intro
I now search for "Welcome to JShell", which is working.
I think this is related to additional issues I am having with this
fix. I used to see JDK-8230872 happen about 1% of the time after the
original fix I had for this CR (8228625). However, now it fails about
9% of the time. It seems that this new fix is making it more likely
that jshell will be in a state that will uncover jmap bugs. If I add
another 10 second delay to the test, all the jmap problems go away.
This started to get me thinking that maybe "jmap --pid" is just not
reliable. We do have a few other tests for this, but I believe they
all wait until the target process has all threads blocked before
issuing the jmap command. This might be why they don't see problems.
In the case of this test, since I don't fully wait for the jshell>
prompt, there is still probably some jshell activity when jmap
attaches. Waiting an extra 10 seconds gets us past this activity, and
likely jshell is blocked waiting for input. In fact even just waiting
1 additional second seems to be long enough.
Chris
On 9/18/19 9:44 PM, Chris Plummer wrote:
I got this to work, although it increased the test time from about
30s to over 3m. I looked into it a bit and it appears to be due to
the size of the generate hprof file. It used to be about 300k, but
now is nearly 7mb. I guess that's because jshell has been run for
longer and probably allocated more data.
I need to do some more testing and a bit of cleanup. I'll get another
review out tomorrow.
Chris
Suddenly the test time is taking
On 9/18/19 5:43 PM, Chris Plummer wrote:
Ok. It was a bit unclear to me why the author went with
Runtime.exec() in the first place. I'll try ProcessTools. That will
probably however, hide 8230872. I might need to write another test
for it.
Chris
On 9/18/19 4:29 PM, Alex Menkov wrote:
You can use jdk.test.lib classes to simplify the things.
Something like
ProcessBuilder pb = new
ProcessBuilder(JDKToolFinder.getTestJDKTool("jshell"));
Process p = ProcessTools.startProcess("JShell", pb,
s -> { // warm-up predicate
return s.contains(">jshell");
});
--alex
On 09/18/2019 15:44, Chris Plummer wrote:
Is there an easy way of doing this? Currently the jshell process
is just spawned using Runtime.exec().
Chris
On 9/18/19 3:01 PM, Alex Menkov wrote:
Hi Chris,
Did you think about waiting for jshell prompt ("jshell>") before
run "jhsdb jmap" command instead of delay or re-tries?
--alex
On 09/18/2019 14:11, Chris Plummer wrote:
Hello,
Please review the following changes:
http://cr.openjdk.java.net/~cjplummer/8228625/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8228625
There are actually numerous ways that JShellHeapDumpTest.java
fails. One is a test bug, being addressed here, and the rest all
seem to be SA bugs. Those are now being covered by JDK-8230872.
All the issues seem to stem from the fact that the test spawns a
jshell process, and then immediately does a "jhsdb jmap" on the
process before jshell has fully started up.
The test bug happens when the jmap succeeds, but jshell has not
yet entered the main java thread. Thus the search for
"JShellToolProvider" in the output fails. It expects
"JShellToolProvider" to be in the output because it is part of a
method name in the main thread, and the test dump all the thread
stacks contained in the jmap generated hprof file. When the test
fails in this way, you can see the stack dump in the output, but
the main thread is missing.
There's a couple of ways to fix this. One is to just add a delay
(10s seems to be more than enough), and the other is to retry
the "jhsdb jmap" command until the stack contains the
JShellToolProvider symbol. I chose the later because doing a 10s
delay masks the SA issues that are now covered by JDK-8230872.
In a way the 10s delay is a better fix, because it makes this
test pass every time, but I did not like that it also hid real
SA problems in JDK-8230872. My plan for now is to do this retry
fix, and then if there are too many failures due to JDK-8230872,
then also add a 10s delay, with the intention of removing it
once JDK-8230872 if fixed. From what I can see, JDK-8230872
failures happen on about 1% of the runs.
I made a few of other changes. One was to no longer redirect
stderr from the jmap process as was done from the following:
processBuilder.redirectError(ProcessBuilder.Redirect.INHERIT);
This causes the output not to appear in the OutputAnalyzer
output, resulting in the following not working:
output.shouldNotContain("null");
Also I added code to dump the output of the jshell process so
you can see if the jshell prompt was ever generated.
thanks,
Chris
