一、Docker啟動異常表現：
1.狀態反復restaring，用命令查看
$docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
21c09be88c11 docker.xxxx.cn:5000/xxx-tes/xxx_tes:1.0.6 "/usr/local/tomcat..." 9 days ago Restarting (1) Less than a second ago xxx10
2.Docker日志有明顯問題：
二、Docker啟動異常的可能原因：
2.1.內存不夠
Docker 啟動至少需要2G內存，首先執行free -mh命令查看剩余內存是否足夠
直接查看內存
$free -mh
total used free shared buff/cache available
Mem: 15G 14G 627M 195M 636M 726M
Swap: 0B 0B 0B
分析日志
有時候一瞬間內存過載溢出，導致部分進程被殺死，看起來內存也是夠用的，事實上docker還是會反復重啟，就需要通過docker日志和系統日志信的息來進一步分析：
分析docker日志
查看docker日志看到內存溢出的信息，要仔細翻閱才能找到信息，并不是在最下面
$docker logs [容器名/容器ID]|less
Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000769990000, 1449590784, 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 1449590784 bytes for committing reserved memory.
# An error report file with more information is saved as:
# //hs_err_pid1.log
Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000769990000, 1449590784, 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 1449590784 bytes for committing reserved memory.
# An error report file with more information is saved as:
# /tmp/hs_err_pid1.log
Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000769990000, 1449590784, 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 1449590784 bytes for committing reserved memory.
# Can not save log file, dump to screen..
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (malloc) failed to allocate 1449590784 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:2756), pid=1, tid=140325689620224
#
# JRE version: (7.0_79-b15) (build )
# Java VM: Java HotSpot(TM) 64-Bit Server VM (24.79-b02 mixed mode linux-amd64 compressed oops)
# Core dump written. Default location: //core or core.1
#
分析系統日志
查看系統日志，發現有大量由于內存溢出，進程被殺死的記錄
$grep -i 'Out of Memory' /var/log/messages
Apr 7 10:04:02 centos106 kernel: Out of memory: Kill process 1192 (java) score 54 or sacrifice child
Apr 7 10:08:00 centos106 kernel: Out of memory: Kill process 2301 (java) score 54 or sacrifice child
Apr 7 10:09:59 centos106 kernel: Out of memory: Kill process 28145 (java) score 52 or sacrifice child
Apr 7 10:20:40 centos106 kernel: Out of memory: Kill process 2976 (java) score 54 or sacrifice child
Apr 7 10:21:08 centos106 kernel: Out of memory: Kill process 3577 (java) score 47 or sacrifice child
Apr 7 10:21:08 centos106 kernel: Out of memory: Kill process 3631 (java) score 47 or sacrifice child
Apr 7 10:21:08 centos106 kernel: Out of memory: Kill process 3634 (java) score 47 or sacrifice child
Apr 7 10:21:08 centos106 kernel: Out of memory: Kill process 3640 (java) score 47 or sacrifice child
Apr 7 10:21:08 centos106 kernel: Out of memory: Kill process 3654 (java) score 47 or sacrifice child
Apr 7 10:27:27 centos106 kernel: Out of memory: Kill process 6998 (java) score 51 or sacrifice child
Apr 7 10:27:28 centos106 kernel: Out of memory: Kill process 7027 (java) score 52 or sacrifice child
Apr 7 10:28:10 centos106 kernel: Out of memory: Kill process 7571 (java) score 42 or sacrifice child
Apr 7 10:28:10 centos106 kernel: Out of memory: Kill process 7586 (java) score 42 or sacrifice child
2.2.端口沖突
該docker監聽端口已經被其他進程占用，一般此種問題容易出現在新部署的服務，或在原有機器上部署新的后臺服務，所以在部署之前應該執行命令檢查端口是否已經被占用，如果上線后發現占有則應改為可用端口再重啟之。
檢查命令： $netstat -nltp|grep [規劃的端口號]
三、對策
3.1.內存不夠的對策：
對策1:
3.1.1 saltstack的minion在運行過久之后，可能占用大量內存，需要將其重啟。重啟命令可能有時并不起作用。主要檢查運行狀態，如果未成功停止，則重新重啟；
對策2:
3.2.2 ELK日志收集程序或者其他java進程占用過高，用top和ps命令排查，謹慎確定進程的作用，在確保不影響業務的情況下，停止相關進程；
對策3:
釋放被占用的內存（buff/cache）：
$sync #將內存數據寫入磁盤
$echo 3 > /proc/sys/vm/drop_caches #釋放被占用的內存
對策4:
有時候并不是buff/cache過高導致內存不夠用，確實是被很多必要的進程消耗掉了內存，那就需要從機器資源分配使用的層面去考慮和解決了。
3.2 端口沖突的對策
對策1:
一般此種問題容易出現在新部署的服務，或在原有機器上部署新的后臺服務，所以在部署之前應該執行命令檢查端口是否已經被占用，如果上線后發現占有則應改為可用端口再重啟之。
檢查命令： $netstat -nltp|grep [規劃的端口號]
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持腳本之家。
