Linux系统及应用问题分析排查工具

Linux服务器上经常遇到一些系统和应用上的问题，如何分析排查，需要利器，下面总结列表了一些常用工具、trace tool；最后也列举了最近hadoop社区在开发发展的分布式系统的trace tool。

概览：

引用linux-performance-analysis-and-tools中图片，说明这些tool试用层次位置

OS系统命令

系统信息（RHEL/Fedora）

• uname -a 或 cat /proc/version #print system information
  • Linux hadoopst2.cm6 2.6.18-164.el5 #1 SMP Tue Aug 18 15:51:48 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux
• uptime
  • 15:42:46 up 674 days, 6 min, 35 users, load average: 1.30, 5.97, 11.53
• cat /etc/redhat-release
  • Red Hat Enterprise Linux Server release 5.4 (Tikanga)
• lsb_release
  • LSB Version:  :core-3.1-amd64:core-3.1-ia32:core-3.1-noarch:graphics-3.1-amd64:graphics-3.1-ia32:graphics-3.1-noarch
• cat /proc/cpuinfo
• cat /proc/meminfo
• lspci - list all PCI devices
• lsusb - list USB devices
• last, lastb - show listing of last logged in users
• lsmod — show the status of modules in the Linux Kernel
• modprobe - add and remove modules from the Linux Kernel

常用命令/工具

• ps
  • To print a process tree: ps -ejH / ps axjf
  • To get info about threads: ps -eLf / ps axms
• ulimit -a
• lsof - list open files, UNIX一切皆文件
  • lsof -p PID
• rpm/yum
  • rpm -qf FILE #文件所属rpm包
  • rpm -ql RPM #rpm包含文件
  • /var/log/yum.log #yum 更新包日志
• /etc/XXX #系统级程序配置目录， 如
  • /etc/yum.repos.d/ yum源配置
• /var/log/XXX #日志目录， 如
  • /var/log/cron #crontab日志，可以查看调度执行情况
• ntpd - Network Time Protocol (NTP) daemon，同步集群中机器时间
• squid - proxy caching server，集群WebUI的代理

系统监控

• mpstat - Report processors related statistics. 注意%sys %iowait值
• vmstat - Report virtual memory statistics
• iostat - Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions.
• netstat - Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships
  • netstat -atpn | grep PID
• ganglia - a scalable distributed monitoring system for high-performance computing systems such as clusters and Grids.
• sar/tsar - Collect, report, or save system activity information; tsar是淘宝自己改进的版本
  • 定时采样（每分钟），可查历史记录（默认5分钟），可弥补ganglia显示更详细信息
• iftop - the "top" bandwidth consumers shown. iftop wiki
• iotop
• vmtouch, Portable file system cache diagnostics and control

网络相关

• telnet/nc IP PORT - 确认目标端口是否可访问，只ping通不一定端口可访问，可能防火墙等禁止
• ifconfig/ifup/ifdown - configure a network interface
• traceroute - print the route packets trace to network host
• nslookup - query Internet name servers interactively
• tcpdump - dump traffic on a network， 类似开源工具 wireshark, netsniff-ng, 更多工具比较
• lynx - a general purpose distributed information browser for the World Wide Web
• tcpcp - allows cooperating applications to pass ownership of TCP connection endpoints from one Linux host to another one.

程序/进程相关

静态信息

• ldconfig - configure dynamic linker run time bindings
  • ldconfig -p | grep SO 查看so是否在link cache中
• ldd - print shared library dependencies， 查看exe或so依赖的so
• nm - list symbols from object files，可grep查找是否存在相关的symbol，是否Undefined.
• readelf - Displays information about ELF files. 可现实elf相关信息，如32/64位，适用的OS，处理器

动态信息

• gdb
• cat /proc/$PID/[cmdline|environ|limits|status|...] - 进程相关信息
• pstack - print a stack trace of a running process
• pmap - report memory map of a process

java相关

• JDK Tools and Utilities
• Java Troubleshooting Tools
• jinfo - print java process information, 如classpath，java.libary.path（jni so目录）
• jstack - print a stack trace of a running java process，可查看死锁情况
• jmap - report memory map of a java process
  • jmap -histo:live 可触发full gc
  • jmap -dump:live,file=$FILE 可dump heap内存，用于jhat等工具debug分析object在heap的占用情况
• jhat - Heap Dump Browser - Starts a web server on a heap dump file (eg, produced by jmap -dump), allowing the heap to be browsed.
  • 起http服务，浏览器访问查看
  • -J-mxXXXm ，分析大文件时需要加大heap大小
  • 若有对象数据超大或内存占用过多，极有可能memory leak
• Memory Analyzer (MAT) - eclipse plugin，Java heap analyzer
  • 可视化工具，但受到机器内存的限制，无法分析太大的heap dump file
• jdb - 可起服务做server，eclipse等工具远程连接调试
• jstat - Java Virtual Machine Statistics Monitoring Tool
• jstatd - Virtual Machine jstat Daemon，可配合jvisualvm
• jvisualvm - Java Virtual Machine Monitoring, Troubleshooting, and Profiling Tool；可远程连接jstatd/jmx, 可视化展示工具：演示
• jvmtop - In a top-like manner, displays JVM internal metrics (e.g. memory information) of running java processes.
• JVM performance optimization JVM开发者写的优化文章
  1. Overview
  2. Compilers
  3. Garbage collection
  4. Concurrently compacting GC
  5. Scalability
• HPROF - Heap Profiler： java -agentlib:hprof

Trace/Debug/Profiling工具

通用工具

• 写log，但系统在线或无法源码时
• strace - trace system calls and signals
  • 示例：strace/ltrace的应用实例
  • 示例：可跟踪系统调用时间，如机器cpu:%sys高的问题

% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 67.90 3966.320849         496   7992161   3050250 futex
 25.80 1507.326693      127093     11860           epoll_wait
....................

• blktrace, generate traces of the i/o traffic on block devices
• ltrace - A library call tracer
• xtrace
• gprof - a performance analysis tool, sampling and call-graph profiling
• valgrind - an instrumentation framework for building dynamic analysis tools. automatically detect many memory management and threading bugs, and profile your programs in detail
• systemtap - a simple command line interface and scripting language for writing instrumentation for a live running kernel plus user-space applications for complex tasks that may require live analysis, programmable on-line response, and whole-system symbolic access.
  • Linux版DTrace（SUN在Solaris上开发的）
  • 功能强大，kernel， user-space app，cross language（java perl python ruby），build-in markers（pg mysql）
  • can write and reuse simple scripts to deeply examine the activities of a live system
  • Data can be extracted, filtered, and summarized quickly and safely, to enable diagnoses of complex performance or functional problems
  • 丰富的 "tapset" script library

java trace工具

• btrace - dynamic tracing tool for the Java platform. UserGuide
  • 基于动态字节码修改技术(Hotswap)来实现运行时java程序的跟踪和替换, 实现原理
  • BTrace使用总结
  • 详细介绍
• byteman - simplifies tracing and testing of Java programs. Can modify a running application without needing to stop and restart it.
  • define rules specifying the side effects you want to inject 而 BTrace类java语法

Distributed Tracing Tools

• Dapper, a Large-Scale Distributed Systems Tracing Infrastructure
• x-trace, a network diagnostic tool designed to provide users and network operators with better visibility into increasingly complex Internet applications.
• HTrace， a tracing framework intended for use with distributed systems written in java
  • Add Tracing to HDFS
  • Update HTrace for HBase

部分内容有引用微博其他童鞋的，如有问题可以及时联系。