即使有足够的RAM可用，Java程序仍无法分配本机内存。
程序在失败后重复崩溃，并出现os_commit异常。
建议更新以调整Java堆等设置。
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 12288 bytes for committing reserved memory.
# 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 (os_linux.cpp:2627), pid=35462, tid=140393234093824
#
# JRE version: Java(TM) SE Runtime Environment (8.0_65-b17) (build 1.8.0_65-b17)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.65-b01 mixed mode linux-amd64 compressed oops)
# Core dump written. Default location: /usr/hdp/share/hst/activity-analyzer/core or core.35462
#
根据日志，您可以看到有足够的可用内存。
Memory: 4k page, physical 264266920k(135968600k free), swap 8393468k(8393468k free)
vm_info: Java HotSpot(TM) 64-Bit Server VM (25.65-b01) for linux-amd64 JRE (1.8.0_65-b17), built on Oct 6 2015 17:16:12 by "java_re" with gcc 4.3.0 20080428 (Red Hat 4.3.0-8)
time: Tue Feb 5 05:54:26 2019
elapsed time: 2928 seconds (0d 0h 48m 48s)
资源利用率
# free -mg
total used free shared buffers cached
Mem: 252 134 117 0 0 25
-/+ buffers/cache: 108 143
Swap: 8 0 8
JMap 输出
# jmap -heap 2820
Attaching to process ID 2820, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.65-b01
using thread-local object allocation.
Parallel GC with 33 thread(s)
Heap Configuration:
MinHeapFreeRatio = 0
MaxHeapFreeRatio = 100
MaxHeapSize = 33554432000 (32000.0MB)
NewSize = 44564480 (42.5MB)
MaxNewSize = 11184635904 (10666.5MB)
OldSize = 89653248 (85.5MB)
NewRatio = 2
SurvivorRatio = 8
MetaspaceSize = 21807104 (20.796875MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 17592186044415 MB
G1HeapRegionSize = 0 (0.0MB)
Heap Usage:
PS Young Generation
Eden Space:
capacity = 9320267776 (8888.5MB)
used = 7558977896 (7208.803077697754MB)
free = 1761289880 (1679.696922302246MB)
81.10258286209995% used
From Space:
capacity = 262668288 (250.5MB)
used = 242645032 (231.40433502197266MB)
free = 20023256 (19.095664978027344MB)
92.37698004869168% used
To Space:
capacity = 346030080 (330.0MB)
used = 0 (0.0MB)
free = 346030080 (330.0MB)
0.0% used
PS Old Generation
capacity = 715653120 (682.5MB)
used = 395523640 (377.2007369995117MB)
free = 320129480 (305.2992630004883MB)
55.267507252675706% used
22626 interned Strings occupying 2218928 bytes.
Java 版本
# java -version
java version "1.8.0_65"
Java(TM) SE Runtime Environment (build 1.8.0_65-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.65-b01, mixed mode)
红帽发行版
# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.6 (Santiago)