64位Ubuntu14.04 tomcat日志报错 There is insufficient memory for the Java Runtime Environment to continue

发现一个应用报错502，查看日志后得知错误信息

Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x00000007d3000000, 536870912, 0) failed; error='Cannot allocate memory' (errno=12)
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (malloc) failed to allocate 536870912 bytes for committing reserved memory.
# An error report file with more information is saved as:
# /data/tomcat/bin/hs_err_pid26832.log

ps -ef是看不到这个应用的。

查看/data/tomcat/bin/hs_err_pid26832.log得知

# There is insufficient memory for the Java Runtime Environment to continue.
# Cannot create GC thread. Out of system resources.
# Possible reasons:
#   The system is out of physical RAM or swap space
#   In 32 bit mode, the process size limit was hit
# Possible solutions:
#   Reduce memory load on the system
#   Increase physical memory or swap space
#   Check if swap backing store is full
#   Use 64 bit Java on a 64 bit OS
#   Decrease Java heap size (-Xmx/-Xms)
#   Decrease number of Java threads
#   Decrease Java thread stack sizes (-Xss)
#   Set larger code cache with -XX:ReservedCodeCacheSize=
# This output file may be truncated or incomplete.
#
#  Out of Memory Error (gcTaskThread.cpp:46), pid=17285, tid=47629249568816
#
# JRE version: 6.0_43-b01
# Java VM: Java HotSpot(TM) 64-Bit Server VM (20.14-b01 mixed mode linux-amd64 compressed oops)

从日志中分析，可能原因有两个：

一、可能物理内存不足

二、在32位操作系统下，系统进程数达到上限了。

然后分析服务器内存，可用物理内存以及swap空间都足够，问题可能发生在系统进程数达到上限（我的64位操作系统也是这个问题）。

通过命令查看系统限制：ulimit -a查看open files的值为1024，不够大，尝试通过设大该值：

1、vi  /etc/security/limits.conf

2、在文件最下方加上如下代码   root - nofile 65535   保存（ubuntu下不能使用* - nofile 65535，不起作用，必须注明用户）

ssh退出后重新登录

此时通过ulimit -a或ulimit -n可以得到结果65535

启动tomcat问题解决