-----Ursprüngliche Nachricht-----
Von: James H. H. Lampert <jam...@touchtonecorp.com.INVALID>
Gesendet: Montag, 6. Februar 2023 18:18
An: Tomcat Users List <users@tomcat.apache.org>
Betreff: Re: AW: Having trouble with Tomcat crashes. Interesting memory
numbers in Manager
Thanks, Herr Hoffmann. Your questions were most helpful in determining
what information to gather and share. And thanks in advance to anybody
else who has any insights.
First, I will note that the seemingly non-sequitur nursery-survivor numbers
aren't just what we see during a crash; they're what we see when it's running
normally.
On 2/4/23 6:13 AM, Thomas Hoffmann (Speed4Trade GmbH) wrote:
Could you describe "crash" in a bit more detail?
Typically, the signed-on users start to get degraded response times, before it
becomes completely unresponsive.
- does the tomcat / java process run but is unresponsive?
Yes. Exactly. And shutting it down (and therefore freeing up the port for a
restart) takes a fairly sizeable amount of time, and leaves a core dump of
approximately 6G size, a Javacore dump of approximately 4M size, and a JIT
dump of approximately 20M size.
- does the java process crash itself (then there should be a logfile written)?
The job does not generally terminate itself, or even respond to a shutdown
request; it has to be forcibly terminated (given that it's running on an AS/400,
this would typically be either from WRKACTJOB, or from an ENDJOB
command, or from their GUI console equivalents).
This may be relevant: even when it is not in this state, the Tomcat server,
when being shut down, tends not to respond readily to shutdown requests.
- Is there any OOM message in the logfiles?
Not out-of-memory, but there are chronic problems with contacting outside
web services (many of them involving Oauth2), and with BIRT reporting.
Around the time of the shutdown, I typically see stuff like:
Unhandled exception
Type=Segmentation error vmState=0x00000000
J9Generic_Signal_Number=00000004 Signal_Number=0000000b
Error_Value=00000000 Signal_Code=00000032
I am not sure whether this is going into catalina.out before or after the job is
forcibly terminated.
- Is the process still alive but CPU at 100% ?
Yes.
We just had a near-miss as I was typing this: CPU pushing up into the high
80s, and the JVM job for Tomcat eating up most of it, but it backed down to
something more normal without my having to intervene, and without any
sign of anybody else intervening.
One of my colleagues managed to get into manager during the near-miss,
and took a screen-shot. The "nursery-allocate" Used was at 400.97M (34%),
"nursery-survivor" as I described last week, "tenured-LOA" Used was at zero
used, and "tenured-SOA" was showing Initial 2918.40M, Total 3648.00M,
Maximum 4864.00M, and Used 1997.72M (41%).
--
JHHL
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