http://digoal126.wap.blog.163.com/w2/blogDetail.do;jsessionid=3949B03DE151DA0E55D807466C5E630B.yqblog35-8010?blogId=fks_087064087086083071087082094069072087087064092081081067080086&showRest=true&p=2&hostID=digoal@126
德哥@Digoal 2013-08-14 15:57
这个错误的原因是库文件版本不正确, 用来老版本, 使用eu-readelf查看stap文件的两个环境变量, 如下 :
[root@db-172-16-3-39 ~]# eu-readelf -d /usr/bin/stap|grep -E “RPATH|RUNPATH” RPATH Library rpath: [/usr/lib64/systemtap] RUNPATH Library runpath: [/usr/lib64/systemtap] 将路径加入到LD_LIBRARY_PATH中.
[root@db-172-16-3-39 ~]# export LD_LIBRARY_PATH=/usr/lib64/systemtap:$LD_LIBRARY_PATH stap现在正常了
[root@db-172-16-3-39 ~]# stap A script must be specified. Systemtap translator/driver (version 1.8/0.152 non-git sources) Copyright (C) 2005-2012 Red Hat, Inc. and others This is free software; see the source for copying conditions. enabled features: AVAHI LIBRPM LIBSQLITE3 NSS BOOST_SHARED_PTR TR1_UNORDERED_MAP NLS Usage: stap [options] FILE Run script in file. or: stap [options] – Run script on stdin. or: stap [options] -e SCRIPT Run given script. or: stap [options] -l PROBE List matching probes. or: stap [options] -L PROBE List matching probes and local variables. 测试 :
[root@db-172-16-3-39 pg94]# vi tps.d probe begin { printf(“hello\n”) exit() } [root@db-172-16-3-39 pg94]# stap tps.d Checking “/lib/modules/2.6.18-274.el5/build/.config” failed with error: No such file or directory Incorrect version or missing kernel-devel package, use: yum install kernel-devel-2.6.18-274.el5.x86_64 这个错误是由于未安装当前正在运行的kernel对应的kernel-devel包.
[root@db-172-16-3-39 pg94]# rpm -qa|grep kernel kernel-headers-2.6.18-274.el5 kernel-xen-devel-2.6.18-274.el5 kernel-xen-2.6.18-274.el5 kernel-2.6.18-274.el5 [root@db-172-16-3-39 ~]# uname -a Linux db-172-16-3-39.sky-mobi.com 2.6.18-274.el5 #1 SMP Fri Jul 22 04:43:29 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux 安装对应的kernel-devel版本.
yum install kernel-devel-2.6.18-274.el5.x86_64 如果yum源中没有这个版本的kernel-devel包, 可以去安装光盘中找一找. 或者同时更新内核版本至新版本.
yum install -y kernel.x86_64 kernel-devel.x86_64 Package kernel-2.6.18-348.12.1.el5.x86_64 already installed and latest version Package kernel-devel-2.6.18-348.12.1.el5.x86_64 already installed and latest version vi /boot/grub/grub.conf default=0 timeout=5 splashimage=(hd0,0)/boot/grub/splash.xpm.gz hiddenmenu title CentOS (2.6.18-348.12.1.el5) root (hd0,0) kernel /boot/vmlinuz-2.6.18-348.12.1.el5 ro root=LABEL=/ rhgb quiet initrd /boot/initrd-2.6.18-348.12.1.el5.img 重启服务器 现在stap工作正常了 :
[root@db-172-16-3-39 postgresql-5e3e8e4]# stap -ve ‘probe begin { log(“hello world”) exit() }’
Pass 1: parsed user script and 85 library script(s) using 146788virt/23676res/3000shr/21384data kb, in 170usr/0sys/173real ms.
Pass 2: analyzed script: 1 probe(s), 2 function(s), 0 embed(s), 0 global(s) using 147316virt/24396res/3224shr/21912data kb, in 10usr/0sys/6real ms.
Pass 3: using cached /root/.systemtap/cache/3b/stap_3b2eaec778ce9832b394535505dde575_838.c
Pass 4: using cached /root/.systemtap/cache/3b/stap_3b2eaec778ce9832b394535505dde575_838.ko
Pass 5: starting run.
hello world
Pass 5: run completed in 0usr/20sys/306real ms.
stap调试好后, 就可以用来跟踪postgresql了. PostgreSQL编译时必须开启dtrace支持. 开启dtrace后, 数据库将启用代码中的探针或跟踪点. PostgreSQL内建探针参考如下 : src/backend/utils/probes.d http://www.postgresql.org/docs/devel/static/dynamic-trace.html 检查你的PostgreSQL是否开启了dtrace支持, 如下 :
pg94@db-172-16-3-39-> pg_config –configure ‘–prefix=/home/pg94/pgsql9.4devel’ ‘–with-pgport=2999’ ‘–with-perl’ ‘–with-tcl’ ‘–with-python’ ‘–with-openssl’ ‘–with-pam’ ‘–without-ldap’ ‘–with-libxml’ ‘–with-libxslt’ ‘–enable-thread-safety’ ‘–with-wal-blocksize=16’ ‘–enable-dtrace’ 如果没有–enable-dtrace, 那么需要重新编译一下你的PostgreSQL软件. stap测试脚本1.
[root@db-172-16-3-39 pg94]# cat postgresql-query.stp global query_time, query_summary probe process(“/home/pg94/pgsql9.4devel/bin/postgres”).mark(“query__start”) { query_time[tid(), $arg1] = gettimeofday_us(); } probe process(“/home/pg94/pgsql9.4devel/bin/postgres”).mark(“query__done”) { p = tid() t = query_time[p, $arg1]; delete query_time[p, $arg1] if (t) { query_summary[p] <<< (gettimeofday_us() – t); } } probe end { printf(“\ntid count min(us) avg(us) max(us)\n”); foreach (p in query_summary) { printf(“%d %d %d %d %d\n”, p, @count(query_summary[p]), @min(query_summary[p]), @avg(query_summary[p]), @max(query_summary[p])); } }
执行stap :
[root@db-172-16-3-39 pg94]# stap postgresql-query.stp 执行以下SQL :
[root@db-172-16-3-39 pg94]# stap postgresql-query.stp digoal=# begin; BEGIN digoal=# select * from test for update; id —- 1 2 3 4 5 6 7 8 9 10 (10 rows) digoal=# end; COMMIT digoal=# select txid_current(); txid_current ————– 5969062 (1 row) 结束stap, 输出 :
[root@db-172-16-3-39 pg94]# stap postgresql-query.stp 按键Ctrl+C, 输出 : tid count min(us) avg(us) max(us) 17112 4 46 3794 14885 这个tid对应PostgreSQL background process
[root@db-172-16-3-39 pg94]# ps -ewf|grep 17112 pg94 17112 17005 0 15:15 ? 00:00:00 postgres: postgres digoal [local] idle digoal=# select pg_backend_pid(); pg_backend_pid —————- 17112 (1 row) [小结] 1. 安装systemtap注意 : — 需要安装kernel相关, 并且版本要一致, 启动的kernel版本也要一致 : kernel kernel-debuginfo kernel-devel
kernel-debuginfo的安装要用到debug源.
[root@db-172-16-3-39 pg94]# cd /etc/yum.repos.d/ [root@db-172-16-3-39 yum.repos.d]# ll total 36 -rw-r–r– 1 root root 1926 Aug 29 2011 CentOS-Base.repo -rw-r–r– 1 root root 631 Aug 29 2011 CentOS-Debuginfo.repo -rw-r–r– 1 root root 626 Aug 29 2011 CentOS-Media.repo -rw-r–r– 1 root root 5390 Aug 29 2011 CentOS-Vault.repo [root@db-172-16-3-39 yum.repos.d]# cat CentOS-Debuginfo.repo # CentOS-Base.repo # # The mirror system uses the connecting IP address of the client and the # update status of each mirror to pick mirrors that are updated to and # geographically close to the client. You should use this for CentOS updates # unless you are manually picking other mirrors. # # All debug packages from all the various CentOS-5 releases # are merged into a single repo, split by BaseArch # # Note: packages in the debuginfo repo are currently not signed # [debug] name=CentOS-5 – Debuginfo baseurl=http://debuginfo.centos.org/5/$basearch/ gpgcheck=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5 enabled=0
这里用到的源名为debug.
yum –enablerepo=debug list kernel-debuginfo yum –enablerepo=debug install kernel-debuginfo 安装细节参考此文 : http://pic.dhe.ibm.com/infocenter/lnxinfo/v3r0m0/topic/liaai.systemTap/liaaisystap_pdf.pdf 2. postgresql编译时必须加上–enable-dtrace参数, 否则stap时会出现类似以下错误.
[root@db-172-16-3-39 pg93]# stap test.stp semantic error: while resolving probe point: identifier ‘process’ at test.stp:3:7 source: probe process(“/opt/pgsql9.3beta2/bin/postgres”).mark(“lock__wait__start”) ^ semantic error: no match semantic error: while resolving probe point: identifier ‘process’ at :8:7 source: probe process(“/opt/pgsql9.3beta2/bin/postgres”).mark(“lock__wait__done”) ^ semantic error: while resolving probe point: identifier ‘process’ at :17:7 source: probe process(“/opt/pgsql9.3beta2/bin/postgres”).mark(“lwlock__wait__start”) ^ semantic error: while resolving probe point: identifier ‘process’ at :22:7 source: probe process(“/opt/pgsql9.3beta2/bin/postgres”).mark(“lwlock__wait__done”) ^ semantic error: while resolving probe point: identifier ‘process’ at :32:7 source: probe process(“/opt/pgsql9.3beta2/bin/postgres”).mark(“lwlock__condacquire__fail”) ^ Pass 2: analysis failed. Try again with another ‘–vp 01’ option.
3. 允许stap需要root权限, 或者将用户加入stapdev或者stapsys, 以及stapusr组. 如果普通用户不加入这两个组, 执行stap将报错 :
pg93@db-172-16-3-39-> stap -ve ‘probe begin { log(“hello world”) exit() }’ You are trying to run systemtap as a normal user. You should either be root, or be part of the group “stapusr” and possibly one of the groups “stapsys” or “stapdev”. Systemtap translator/driver (version 1.8/0.152 non-git sources) 加完组后正常 # usermod -G stapdev,stapusr pg94 pg94@db-172-16-3-39-> stap -ve ‘probe begin { log(“hello world”) exit() }’ Pass 1: parsed user script and 85 library script(s) using 148892virt/23772res/3068shr/21396data kb, in 160usr/10sys/172real ms. Pass 2: analyzed script: 1 probe(s), 2 function(s), 0 embed(s), 0 global(s) using 149420virt/24492res/3292shr/21924data kb, in 10usr/0sys/6real ms. Pass 3: translated to C into “/tmp/stapcqtmUe/stap_758dbd41826239e5e3211a815f6bfc58_838_src.c” using 149420virt/24760res/3540shr/21924data kb, in 0usr/0sys/0real ms. Pass 4: compiled C into “stap_758dbd41826239e5e3211a815f6bfc58_838.ko” in 910usr/110sys/1028real ms. Pass 5: starting run. hello world Pass 5: run completed in 10usr/20sys/307real ms.
本文就介绍到这里, 下次将介绍如何使用postgresql的探针.
[参考]
1. http://pgfoundry.org/projects/dtrace/ 2. http://www.fosslc.org/drupal/content/probing-postgresql-dtrace-and-systemtap 3. http://www.postgresql.org/docs/devel/static/dynamic-trace.html 4. http://www.postgresql.org/docs/devel/static/install-procedure.html 5. http://www.ppurl.com/2011/05/dtrace-dynamic-tracing-in-oracle-solaris-mac-os-x-and-freebsd.html 6. http://www.emm.usp.br/downloads/pg/PG_perf_bootcamp.pdf 7. https://wiki.postgresql.org/wiki/DTrace 8. http://www.ppurl.com/?s=systemtap 9. http://www.ibm.com/developerworks/cn/linux/l-systemtap/ 10. http://sourceware.org/systemtap/wiki/HomePage 11. http://fruli.krunch.be/~krunch/systemtap-osdcfr-20101010.pdf 12. http://blog.endpoint.com/2009/05/postgresql-with-systemtap.html 13. https://www.evernote.com/shard/s48/sh/1ccb0466-79b7-4090-9a5d-9371358ac54d/b8434e3e3b3130ce72422b9ae067e7b9 14. http://pic.dhe.ibm.com/infocenter/lnxinfo/v3r0m0/topic/liaai.systemTap/liaaisystap_pdf.pdf 15. http://linux.chinaunix.net/techdoc/develop/2008/12/28/1055546.shtml 16. http://os.51cto.com/art/201305/395819.htm
17. https://access.redhat.com/site/documentation/Red_Hat_Enterprise_Linux/?locale=en-US
