Hi gays,
I'm designing a Apache as a reverse proxy using a home made perl
script for cookie support.
I needs some advises to design Apache as a reverse proxy for many web
apps(~ 20 servers)
There will be 500 users using this system 24/7.
Each users will have 2 permanents HTTPS connections using chunk encoding and
1 connection using HTTPS keep alive mechanism.
Finally Apache will have to process 1000 simultaneous permanent
HTTPS connections and 500 HTTPS connections.
An other point is that Apache will have to rewrite the HTTP Location
header to support HTTP 302 redirection and authenticate users using a
perl module to provide a BASIC + cookie authentication.
I mades some tests with the Apache ab product on apache v2.2.9
my harware configuration is :
# cat /proc/cpuinfo
processor : 0
model name : Intel(R) Pentium(R) 4 CPU 2.80GHz
processor : 1
model name : Intel(R) Pentium(R) 4 CPU 2.80GHz
# top
Mem: 2067440k total, 691124k used, 1376316k free, 190704k buffers
# apachectl -V
Server version: Apache/2.2.9 (Unix)
Server built: Jul 8 2008 16:17:39
Server's Module Magic Number: 20051115:15
Server loaded: APR 1.2.7, APR-Util 1.2.7
Compiled using: APR 1.2.7, APR-Util 1.2.7
Architecture: 32-bit
Server MPM: Prefork
threaded: no
forked: yes (variable process count)
Server compiled with....
-D APACHE_MPM_DIR="server/mpm/prefork"
-D APR_HAS_SENDFILE
-D APR_HAS_MMAP
-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
-D APR_USE_SYSVSEM_SERIALIZE
-D APR_USE_PTHREAD_SERIALIZE
-D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
-D APR_HAS_OTHER_CHILD
-D AP_HAVE_RELIABLE_PIPED_LOGS
-D DYNAMIC_MODULE_LIMIT=128
-----------------httpd.conf-----------------
<IfModule prefork.c>
MinSpareServers 50
MaxSpareServers 50
StartServers 50
ServerLimit 10000
MaxClients 500
MaxRequestsPerChild 5000
</IfModule>
----------------END ----------------------
I choose MaxClients=500 because it's an estimation of the child
process memory usage.
there is the calculation :
Total_RAM_free
MaxClients = ---------------------------------------
Max_Process_Size - Shared_RAM_per_Child
and i get this values with top on a worker child process
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ DATA COMMAND
9345 daemon 16 0 27540 9868 3660 R 5 0.5 0:00.19 6084 httpd
Shared memory per process = ~ 3,5Mb (3660)
Memory per Process = 6,084 Mb
so I calculate Max Client = 1300 Mb / (6,084 - 3660) = 540 processes,
I prefered gaving some memory margin in case of ...
Do you agree with this result ?
I tests 500 simultaneous connections with a total of 10 000 requests.
I aims to test Apache in a
heavy load and simulates 500 permanent connections but the result was
not very good :
Document Path: /uc/favicon.ico
Document Length: 1022 bytes
Concurrency Level: 500
Time taken for tests: 549.188 seconds
Complete requests: 10000
Failed requests: 264
(Connect: 0, Receive: 0, Length: 264, Exceptions: 0)
Write errors: 0
Non-2xx responses: 2
Total transferred: 13543827 bytes
HTML transferred: 9951006 bytes
Requests per second: 18.21 [#/sec] (mean)
Time per request: 27459.375 [ms] (mean)
Time per request: 54.919 [ms] (mean, across all concurrent requests)
Transfer rate: 24.08 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 63 10873 13533.9 9016 130391
Processing: 47 15784 28431.9 9828 321688
Waiting: 0 12616 27897.6 6516 318703
Total: 469 26657 34939.1 19484 341219
Percentage of the requests served within a certain time (ms)
50% 19484
66% 22094
75% 24922
80% 28547
90% 45891
95% 82531
98% 175422
99% 219375
100% 341219 (longest request)
So I realize that the average time per request was very high !
Time per request: 27459.375 [ms]
Do I need a better harware ?? or is my configuration not optimal ? (I
used this doc :
http://perl.apache.org/docs/1.0/guide/performance.html#Performance_Tuning_by_Tweaking_Apache_Configuration)
Ie : to support fully 1500 processes : 1500* (6,084 - 3660) = 3600 Mb RAM
And a last question, how do apache process chunk encoding requests ?
is it allowing 1 process per connection ? so for 1000 simultaneous
requests it will require 1000 processes ?
thanks a lot :)
--
Sylvain Beaux
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