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Anyone knows a downloadable documentation for jQuery. Their site is so slow that makes referencing impossible. This is an recurring issue that has happened for quite a few months. Is the traffic too much for them to handle?
Labels: javascript, jquery
posted by trungson @ 8:15 AM
0 comments
For a jQuery newbie, I was unsure how to only select the TR's of the main table and not TR's within sub-tables. Tried this that (children(), siblings()) and a bunch of selectors and found out the easy way ('#mytable > tbody > tr') How easy! :)
Labels: jquery
posted by trungson @ 11:27 AM
0 comments
If you're running APC with PHP, you have the option to download apc.php to view, monitor the usage/stats. However, the default authentication is very open. Without any credential, anyone can view the running stats and also the cached filenames (a simple search on "APC INFO" will show some site running APC). The login is to view per-directory file caching. So if you want to require login credential on ALL access change this code: to this:
posted by trungson @ 1:39 PM
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If you run "pecl install [something]" and get this error: "Fatal error: Allowed memory size of 8388608 bytes exhausted (tried to allocate xxx bytes)", you want to change "/usr/bin/pecl" (or run "locate pecl" to see where it is) and specify a larger memory limit.
#!/bin/sh
exec /usr/bin/php -C -n -q -d include_path=/usr/share/pear \
-d output_buffering=1 /usr/share/pear/peclcmd.php "$@"
becomes
#!/bin/sh
exec /usr/bin/php -C -n -q -d include_path=/usr/share/pear \
-d memory_limit=16M -d output_buffering=1 /usr/share/pear/peclcmd.php "$@"
Labels: sysadmin
posted by trungson @ 10:00 AM
0 comments
For busy servers, ip_conntrack can fill up quickly and must be monitored or you will get intermittent packet drops. Check var/log/messages for these error messages. Couple values can be adjusted to the kernel:
more /proc/sys/net/ipv4/netfilter/ip_conntrack_count more /proc/sys/net/ipv4/netfilter/ip_conntrack_max => count should be less than max, if it's near the maximum value, increase max more /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_established => default 5 days, might want to lower it echo 0 > /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_loose
Labels: sysadmin
posted by trungson @ 11:42 AM
0 comments
Hmm, another day, another bug: #33499. This time it is mod_deflate and PHP don't play well together. PHP makes a GIF/JPG file and yet mod_deflate still compress it. Solution: use mod_filter (which only available from 2.1), or disable Apache's compression for PHP files and let PHP do the compression via ob_start('ob_gzhandler');
Labels: sysadmin
posted by trungson @ 1:37 PM
0 comments
This snippet displays Active, Passive and Established connections reported by "netstat --statistics" for saving into RRD or other monitoring tools.
Labels: sysadmin
posted by trungson @ 10:23 AM
0 comments
Both run on the same server: Apache/2.0.59 (port 80) & lighttpd 1.4.19 (port 8080). 2 tests: dynamic & static files. To make things a little realistic, it's from a EU client to a US server.
Server Software: Apache
Server Port: 80
Document Length: 824 bytes
Time taken for tests: 36.51463 seconds
Total transferred: 1213118 bytes
HTML transferred: 847886 bytes
Requests per second: 27.74 [#/sec] (mean)
Time per request: 360.515 [ms] (mean)
Time per request: 36.051 [ms] (mean, across all concurrent requests)
Transfer rate: 32.84 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 158 158 0.3 158 162
Processing: 174 200 26.4 191 340
Waiting: 173 199 26.3 191 340
Total: 332 358 26.4 349 498
Server Software: lighttpd/1.4.19
Server Port: 8080
Document Length: 921 bytes
Time taken for tests: 35.406200 seconds
Total transferred: 1202655 bytes
HTML transferred: 857071 bytes
Requests per second: 28.24 [#/sec] (mean)
Time per request: 354.062 [ms] (mean)
Time per request: 35.406 [ms] (mean, across all concurrent requests)
Transfer rate: 33.16 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 158 158 0.6 158 167
Processing: 172 193 29.0 183 383
Waiting: 172 192 29.0 183 383
Total: 330 351 29.1 341 541
Apache: 27.74 requests/sec
Server Software: Apache
Server Port: 80
Document Length: 14781 bytes
Time taken for tests: 63.858434 seconds
Total transferred: 15060000 bytes
HTML transferred: 14781000 bytes
Requests per second: 15.66 [#/sec] (mean)
Time per request: 638.584 [ms] (mean)
Time per request: 63.858 [ms] (mean, across all concurrent requests)
Transfer rate: 230.31 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 157 158 0.5 158 164
Processing: 476 478 4.6 478 549
Waiting: 158 159 4.0 159 228
Total: 634 636 4.6 636 707
Server Software: lighttp/1.4.19
Server Port: 8080
Document Length: 14781 bytes
Time taken for tests: 63.736261 seconds
Total transferred: 14992000 bytes
HTML transferred: 14781000 bytes
Requests per second: 15.69 [#/sec] (mean)
Time per request: 637.363 [ms] (mean)
Time per request: 63.736 [ms] (mean, across all concurrent requests)
Transfer rate: 229.70 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 157 158 0.4 158 160
Processing: 476 478 2.2 478 491
Waiting: 158 158 1.5 159 166
Total: 634 636 2.3 636 649
Apache 15.66 requests/secApache is very decent when there is a low concurrency level (about 10-20). When taken into account the stability, features, modules, it's an excellent choice. Lighttpd under high load although can perform very well, it does suffer from an issue with PHP (current with 1.4.19 and 5.1.6), its backend fast-cgi became overloaded and gave out 500 errors to clients. Bad lighty, or bad PHP! Hope they got it fixed in 1.5 or some future version of PHP
Labels: sysadmin
posted by trungson @ 5:48 PM
0 comments
# netstat -tan | grep ':80 ' | awk '{print $6}' | sort | uniq -c
Sample Output:
15 CLOSING
26 ESTABLISHED
31 FIN_WAIT1
7 FIN_WAIT2
14 LAST_ACK
2 LISTEN
24 SYN_RECV
2428 TIME_WAIT
Labels: sysadmin
posted by trungson @ 10:53 AM
0 comments
If not, you're wasting overhead on checking and invalidating the query cache, for a large/busy query cache, it gets more expensive. Thus, the lesson is to know which query should not be cached and explicitly use "SELECT SQL_NO_CACHE ..." in your SQL statement. It means tables with many UPDATES/INSERTS should not use query caching.
Labels: mysql
posted by trungson @ 5:33 PM
0 comments
Just for the fun of it. Here is what happens:
[root@s10 ~]# cd / [root@s10 /]# dir bin dev initrd lost+found misc opt sbin srv tmp var boot etc lib media mnt proc selinux sys usr [root@s10 /]# rm -rf * rm: cannot remove directory `boot': Device or resource busy rm: cannot remove directory `dev/shm': Device or resource busy rm: cannot remove `dev/pts/1': Operation not permitted rm: `proc/asound/ICH' changed dev/ino: Operation not permitted [root@s10 /]# [root@s10 /]# dir -bash: /usr/bin/dir: /lib/ld-linux.so.2: bad ELF interpreter: No such file or directory [root@s10 /]# ll -bash: ls: command not found [root@s10 /]# reboot -bash: /sbin/reboot: /lib/ld-linux.so.2: bad ELF interpreter: No such file or directorySince the processes are still running, SSH still accept connections, but cannot sign in, can't run anything either. Was it fun?!
Labels: sysadmin
posted by trungson @ 3:51 PM
0 comments
Labels: firefox performance
posted by trungson @ 11:17 AM
0 comments
That operation will always require a disk read, which is rather expensive, especially for larger tables. For example, for a 500MB table in my test, it takes 0.23 seconds just for this query. I thought the table schema should not depend on its size. Guess there is something more technical than my basic understanding.
Labels: mysql
posted by trungson @ 9:16 AM
0 comments
Labels: code
posted by trungson @ 9:43 AM
0 comments