Tal,
I've been thowing requests at the Prudence test app for the last 20
minutes or so. I do see that it uses a lot of metaspace, close to 50M in
my case. The test app seems to load/unload 2 classes per request with
Rhino compared to 4 classes per request with Nashorn, which is probably
due to differences in bytecode generation between the two engines.
I don't yet see metaspace usage growing beyond that limit, or generating
GC warnings. Maybe I haven't been running it long enough.
I'm wondering if maybe metaspace is tight from the very beginning, and
the GC problems are caused by spikes in load (e.g. concurrent requests)?
Also, are you aware of new classes being generated for each request? Are
you evaluating script files for each request? It would be more efficient
to evaluate the script just once and then reuse it for subsequent requests.
Hannes
Am 2014-01-09 17:21, schrieb Tal Liron:
You may download the latest release of Prudence, run it and bombard it
with hits (use ab or a similar tool):
http://threecrickets.com/prudence/download/
To get the GC logs, start it like so:
JVM_SWITCHES=\
-Xloggc:/full/path/to/logs/gc.log \
-XX:+PrintGCDetails \
-XX:+PrintTenuringDistribution \
sincerity start prudence
To bombard it:
ab -n 50000 -c 10 "http://localhost:8080/prudence-example/";
Of course, you may also want to restrict the JVM heap size so it will
happen sooner. I think. I actually don't understand JVM 8 GC at all,
but you guys do, so have a go. All I can tell you is that I have a
server running live on the Internet, which I have to restart every 3
days due to this issue.
Unfortunately, I don't have an easy way to isolate the problem to
something smaller. However, I would think there's probably an
advantage in using something as big as possible -- you can probably
get very rich dumps of what is polluting the heap.
On 01/10/2014 12:00 AM, Marcus Lagergren wrote:
Tal - The GC people 10 meters behind me want to know if you have a
repro of your full GC to death problem that they can look at? They’re
interested.
/M
On 09 Jan 2014, at 16:29, Kirk Pepperdine <k...@kodewerk.com> wrote:
Hi Marcus,
Looks like some of the details have been chopped off. Is there a GC
log available? If there is a problem with MethodHandle a work around
might be a simple as expanding perm.. but wait, this is meta space
now and it should grow as long as your system has memory to give to
the process. The only thing I can suggest is that the space to hold
compressed class pointers is a fixed size and that if Nashorn is
loading a lot of classes is that you consider making that space
larger. Full disclosure, this isn’t something that I’ve had a chance
to dabble with but I think there is a flag to control the size of
that space. Maybe Colleen can offer better insight.
Regards,
Kirk
On Jan 9, 2014, at 10:02 AM, Marcus Lagergren
<marcus.lagerg...@oracle.com> wrote:
This almost certainly stems from the implementation from
MethodHandle combinators being implemented as lambda forms as
anonymous java classes. One of the things that is being done for
8u20 is to drastically reduce the number of lambda forms created.
I don’t know of any workaround at the moment. CC:ing
hotspot-compiler-dev, so the people there can elaborate a bit.
/M
On 06 Jan 2014, at 06:57, Benjamin Sieffert
<benjamin.sieff...@metrigo.de> wrote:
Hi everyone,
we have been observing similar symptoms from 7u40 onwards (using
nashorn-backport with j7 -- j8 has the same problems as 7u40 and
7u45...
7u25 is the last version that works fine) and suspect the cause to
be the
JSR-292 changes that took place there. Iirc I already asked over
on their
mailing list. Here's the link:
http://mail.openjdk.java.net/pipermail/mlvm-dev/2013-December/005586.html
The fault might as well lie with nashorn, though. It's certainly
worth
investigating.
Regards
2014/1/4 Tal Liron <tal.li...@threecrickets.com>
Thanks! I didn't know of these. I'm not sure how to read the log,
but this
doesn't look so good. I get a lot of "allocation failures" that
look like
this:
Java HotSpot(TM) 64-Bit Server VM (25.0-b63) for linux-amd64 JRE
(1.8.0-ea-b121), built on Dec 19 2013 17:29:18 by "java_re" with
gcc 4.3.0
20080428 (Red Hat 4.3.0-8)
Memory: 4k page, physical 2039276k(849688k free), swap
262140k(256280k
free)
CommandLine flags: -XX:InitialHeapSize=32628416
-XX:MaxHeapSize=522054656
-XX:+PrintGC -XX:+PrintGCDetails -XX:+PrintGCTimeStamps
-XX:+PrintTenuringDistribution -XX:+UseCompressedClassPointers
-XX:+UseCompressedOops -XX:+UseParallelGC
0.108: [GC (Allocation Failure)
Desired survivor size 524288 bytes, new threshold 7 (max 15)
[PSYoungGen: 512K->496K(1024K)] 512K->496K(32256K), 0.0013194 secs]
[Times: user=0.01 sys=0.00, real=0.00 secs]
On 01/04/2014 10:02 PM, Ben Evans wrote:
-Xloggc:<pathtofile> -XX:+PrintGCDetails
-XX:+PrintTenuringDistribution
--
Benjamin Sieffert
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