>+ Somebody reported that Tomcat stalls at approx. 40 simultaneous requests.
>
>+ Linux usually treat 100 apache better then one JVM with 100 threads inside
>(my personal opinion, no serious tests were made); I have no idea about
>Solaris and Windows.
>
Some notes re my experience pushing on this (apache/tomcat and tomcat load)
1) I've successfully pushed 1000 parallel requests through tomcat w/ no
problem
Somebody scream -- there's bs going on here. Actually, due to test harness
time in setting up threads some threads finished before all 1000 threads
setup.
I experienced a large difference in how many threads successfully
handled (and
elapsed time as viewed client side) depending on server memory, -Xmx
setting, and JVM.
2) I can't actually pinpoint where the max/min of the response curve is on
this, but in a server with limited memory (and cpu?) resources having
the combo
apache-tomcat can be worse than tomcat alone because of memory
swap. So if you have heavy simultaneous requests load the swap time can
be worse than the tomcat-slow time (assuming tomcat threads alone
to bump into swap memory). For most people this is not an issue,
but on memory constrained servers (i.e. 64M RAM) it is a problem.
Some data points where client and server on same system that's not memory
constrained (750 Athlon, 3/4G RAM, debian unstable, 2.4.5 kernel):
600 parallel
#/s avg max avg max
static jetty 8-9 .003-.009 .212@300 .003 .128
static tomcat 8-9 .008-.016 .670@600 .016 .670
soap jetty 6-8 .042-.330 2.300@200 .039 .715
soap tomcat 5-8 .047-2.826 4.837@50 .047 .722
So, at 600 parallel requests I saw tomcat responding worse
case less than a second for both static and soap (read servlet)
response. Although other loads saw response times as bad
as 2.3 sec (jetty) and 4.8 sec (tomcat) which I assume were due
to garbage collection holdups.
Contrast w/ memory constrained server apache static
responses over a network (several states separating
client/server, times in milliseconds):
400 parallel calls to Apache ...
min 418, max 48664, average 26315, count 400
maximum number of simultaneous threads: 400
approximat requests per second: 7
Note 26 sec average response time and 48 sec
max response time. Test page was bare minimum
<html><head></head><body>test</body></html>
type of file.
While I'm tossing out crude (and milage will vary)
numbers, Blackdown 1.3.0 (I know 1.3.1 is out, haven't benched)
versus IBM jvm 1.3.0 (recent download) on Linux:
600 parallel
#/s avg max avg max
static black. 55-158 .006-.010 .205@600 .007 .205
static ibm 8-9 .008-.016 .670@600 .016 .670
soap black. 17-26 .048-1.387 2.976@100 .296 1.812
soap ibm 5-8 .047-2.826 4.837@50 .047 .722
Needless to say, it appears that someone optimized blackdown
for some of these tasks. BTW, servlet container was tomcat 3.2.2.
There's also a developer at our shop who's interested in
looking at green versus native threads on linux in the belief
that the green threads may out perform native under heavy
load. I haven't tested that variation.
CONCLUSION: You really need to study your
own working load and server env. to assess optimum
combo of apache or apache-tomcat.
Heitzso
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