>> Yes, it's standard synchronized thread pool
>> implementation, GFv3.1
>> will have more optimized implementation, which will
>> be less
>> synchronized, it could slightly improve perf.
>> numbers. But I don't
>> think this thread pool is the narrow place in your
>> testing.
>
> When doing sampling over longer periods of time, this problem shows
> up very regularly, like once every 5-10 seconds.
> New pool sounds interesting. Do you know if it is possible to
> somehow backport it and do some tests with the new pool? Or maybe
> its simply easier to try GF3v1?
Yes, you can try the latest GFv3.1 nightly build [1] and set thread
pool size the way that minThreads=maxThreads.
[1]
http://download.java.net/glassfish/v3.1/nightly/
WBR,
Alexey.
>> I've checked the dump.
>> You have a lot of worker threads. which may cause
>> redundant CPU
>> thrashing. Just out of curiosity, can you create
>> similar test, which
>> doesn't access DB, but let's say runs some
>> calculation logic instead,
>> and check if you'll be able to load CPUs. This way we
>> will be able to
>> recognize if DB access is the narrow place or not.
>>
>
> Yes, i tried running a crypto on a random string for each request to
> a HTTP servlet and return it to the client, like so:
>
> [code]
> public synchronized String encrypt() {
> String plaintext = "" + new Random().nextDouble();
> MessageDigest md = null;
> try {
> md = MessageDigest.getInstance("SHA");
> } catch (NoSuchAlgorithmException e) {
> throw new RuntimeException(e.getMessage());
> }
> try {
> md.update(plaintext.getBytes("UTF-8"));
> } catch (UnsupportedEncodingException e) {
> throw new RuntimeException(e.getMessage());
> }
> byte raw[] = md.digest();
> String hash = (new BASE64Encoder()).encode(raw);
> return hash;
> }
> [/code]
>
> Still we cannot get the CPU loaded to more than around ~65%.
>
> During this particular test, i also watched
> "sun.rt._sync_ContendedLockAttempts" by doing "jstat -J-
> Djstat.showUnsupported=true -snap <pid> | grep _sync_"..
>
> Seems we have over 5000 lock conflicts every second...
> [Message sent by forum member 'ekrisjo']
>
> http://forums.java.net/jive/thread.jspa?messageID=470137
>
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