Robinson, Eric wrote:
What kind of machine are you running these 163/164
instances of Tomcat on, and when you are running them,
what /does/ "free" say ?
I have two different servers with 164 instances of tomcat. Both servers
have 2x quad-core 2.8Ghz Xeon processors with 32GB RAM. On the first
server (app03), most instances of tomcat are configured with 64MB of
Java heap. About 20% of them have 96-256MB. I almost never reboot this
server (current uptime 61 days). Here's 'free' from app03.
[r...@app03 ~]# free
total used free shared buffers
cached
Mem: 33265832 30570260 2695572 0 296976
4562784
-/+ buffers/cache: 25710500 7555332
Swap: 2031608 0 2031608
On the other server (app04), all instances of tomcat are configured with
512MB Java heap (-ms512M -mx512M). After 4 or 5 days of uptime, the
server starts to swap a little. Then I reboot it and it is fine for
several more days. As you can see from the following, it is about time
for a reboot. If I do not reboot it tonight, by tomorrow or the next day
it may be up to 1-2GB of swap. (It actually doesn't slow the server down
much though. sar shows that it runs about 90% idle anyway, including
iowait.
[r...@app03 ~]# ssh app04 free
total used free shared buffers
cached
Mem: 33265832 32965812 300020 0 191248
3842092
-/+ buffers/cache: 28932472 4333360
Swap: 2031608 4288 2027320
That is very interesting information, thank you.
Intuitively, I would have never thought that it was /possible/ to run 160 or so instances
of Tomcat on anything but some type of very expensive hardware.
Granted, dual-Xeon CPU mainboards with 32 GB are not the low-end, but still.
One tends to forget how many megabytes fit in one gigabyte, and 160 X 64 MB is actually
"only" 10 GB.
The data above, and your comments, seem to make unlikely the OOM hypothesis, unless you
have one application suddenly acting up.
On which of those servers is the one Tomcat instance dying ? on both ? Is that Tomcat
instance running an application which the other ones don't ?
What kind of memory usage do the Tomcat instances have (in total, including the Heap) ? Do
you start them with any kind of other memory-related parameter for the JVM apart from -Xms
and -Xmx ?
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