集群节点进程神秘消失现象描述接到告警和运维反馈一个 RocketMQ 的节点不见了。此类现象在以前从未发生过消失肯定有原因开始查找日志从集群的 broker.log、stats.log、storeerror.log、store.log、watermark.log 到系统的 message 日志没发现错误日志。集群流量出入在正常水位、CPU 使用率、CPU Load、磁盘 IO、内存、带宽等无明显变化。原因分析继续查原因最终通过 history 查看了历史运维操作。发现运维同学在启动 Broker 时没有在后台启动而是在当前 session 中直接启动了。sh bin/mqbroker -c conf/broker-a.conf问题即出现在此命令当 session 过期时 Broker 节点也就退出了。解决方法标准化运维操作对运维的每次操作进行评审将标准化的操作实现自动化运维就更好了。正确启动 Broker 方式nohup sh bin/mqbroker -c conf/broker-a.conf Master 节点 CPU 莫名飙高现象描述RocketMQ 主节点 CPU 频繁飙高后回落业务发送超时严重由于两个从节点部署在同一个机器上从节点还出现了直接挂掉的情况。主节点 CPU 毛刺截图从节点 CPU 毛刺截图说明中间缺失部分为掉线没有采集到的情况。系统错误日志一2020-03-16T17:56:07.50571508:00 VECS0xxxx kernel: [] ? __alloc_pages_nodemask0x7e1/0x960 2020-03-16T17:56:07.50571708:00 VECS0xxxx kernel: java: page allocation failure. order:0, mode:0x20 2020-03-16T17:56:07.50571908:00 VECS0xxxx kernel: Pid: 12845, comm: java Not tainted 2.6.32-754.17.1.el6.x86_64 #1 2020-03-16T17:56:07.50572108:00 VECS0xxxx kernel: Call Trace: 2020-03-16T17:56:07.50572408:00 VECS0xxxx kernel: [] ? __alloc_pages_nodemask0x7e1/0x960 2020-03-16T17:56:07.50572608:00 VECS0xxxx kernel: [] ? dev_queue_xmit0xd0/0x360 2020-03-16T17:56:07.50572908:00 VECS0xxxx kernel: [] ? ip_finish_output0x192/0x380系统错误日志二30 2020-03-27T10:35:28.76990008:00 VECSxxxx kernel: INFO: task AliYunDunUpdate:29054 blocked for more than 120 seconds. 31 2020-03-27T10:35:28.76993208:00 VECSxxxx kernel: Not tainted 2.6.32-754.17.1.el6.x86_64 #1 32 2020-03-27T10:35:28.77165008:00 VECS0xxxx kernel: echo 0 /proc/sys/kernel/hung_task_timeout_secs disables this message. 33 2020-03-27T10:35:28.77463108:00 VECS0xxxx kernel: AliYunDunUpda D ffffffff815592fb 0 29054 1 0x10000080 34 2020-03-27T10:35:28.77750008:00 VECS0xxxx kernel: ffff8803ef75baa0 0000000000000082 ffff8803ef75ba68 ffff8803ef75ba64说明系统日志显示错误“page allocation failure”和“blocked for more than 120 second”错误日志目录 /var/log/messages。GC 日志2020-03-16T17:49:13.7850800: 13484510.599: Total time for which application threads were stopped: 0.0072354 seconds, Stopping threads took: 0.0001536 seconds 2020-03-16T18:01:23.1490800: 13485239.963: [GC pause (G1 Evacuation Pause) (young) 13485239.965: [G1Ergonomics (CSet Construction) start choosing CSet, _pending_cards: 7738, predicted base time: 5.74 ms, remaining time: 194.26 ms, target pause time: 200.00 ms] 13485239.965: [G1Ergonomics (CSet Construction) add young regions to CSet, eden: 255 regions, survivors: 1 regions, predicted young region time: 0.52 ms] 13485239.965: [G1Ergonomics (CSet Construction) finish choosing CSet, eden: 255 regions, survivors: 1 regions, old: 0 regions, predicted pause time: 6.26 ms, target pause time: 200.00 ms] , 0.0090963 secs] [Parallel Time: 2.3 ms, GC Workers: 23] [GC Worker Start (ms): Min: 13485239965.1, Avg: 13485239965.4, Max: 13485239965.7, Diff: 0.6] [Ext Root Scanning (ms): Min: 0.0, Avg: 0.3, Max: 0.6, Diff: 0.6, Sum: 8.0] [Update RS (ms): Min: 0.1, Avg: 0.3, Max: 0.6, Diff: 0.5, Sum: 7.8] [Processed Buffers: Min: 2, Avg: 5.7, Max: 11, Diff: 9, Sum: 131] [Scan RS (ms): Min: 0.0, Avg: 0.0, Max: 0.1, Diff: 0.1, Sum: 0.8] [Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.3] [Object Copy (ms): Min: 0.2, Avg: 0.5, Max: 0.7, Diff: 0.4, Sum: 11.7] [Termination (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff: 0.0, Sum: 0.3] [Termination Attempts: Min: 1, Avg: 1.0, Max: 1, Diff: 0, Sum: 23] [GC Worker Other (ms): Min: 0.0, Avg: 0.2, Max: 0.3, Diff: 0.3, Sum: 3.6] [GC Worker Total (ms): Min: 1.0, Avg: 1.4, Max: 1.9, Diff: 0.8, Sum: 32.6] [GC Worker End (ms): Min: 13485239966.7, Avg: 13485239966.9, Max: 13485239967.0, Diff: 0.3] [Code Root Fixup: 0.0 ms] [Code Root Purge: 0.0 ms] [Clear CT: 0.9 ms] [Other: 5.9 ms] [Choose CSet: 0.0 ms] [Ref Proc: 1.9 ms] [Ref Enq: 0.0 ms] [Redirty Cards: 1.0 ms] [Humongous Register: 0.0 ms] [Humongous Reclaim: 0.0 ms] [Free CSet: 0.2 ms] [Eden: 4080.0M(4080.0M)-0.0B(4080.0M) Survivors: 16.0M-16.0M Heap: 4176.5M(8192.0M)-96.5M(8192.0M)] [Times: user0.05 sys0.00, real0.01 secs]说明GC 日志正常。Broker 错误日志2020-03-16 17:55:15 ERROR BrokerControllerScheduledThread1 - SyncTopicConfig Exception, x.x.x.x:10911 org.apache.rocketmq.remoting.exception.RemotingTimeoutException: wait response on the channel timeout, 3000(ms) at org.apache.rocketmq.remoting.netty.NettyRemotingAbstract.invokeSyncImpl(NettyRemotingAbstract.java:427) ~[rocketmq-remoting-4.5.2.jar:4.5.2] at org.apache.rocketmq.remoting.netty.NettyRemotingClient.invokeSync(NettyRemotingClient.java:375) ~[rocketmq-remoting-4.5.2.jar:4.5.2]说明通过查看 RocketMQ 的集群和 GC 日志只能说明但是网络不可用造成主从同步问题并未发现 Broker 自身出问题了。原因分析系统使用 CentOS 6内核版本为 2.6。通过摸排并未发现 broker 和 GC 本身的问题却发现了系统 message 日志有频繁的“page allocation failure”和“blocked for more than 120 second”错误。所以将目光聚焦在系统层面通过尝试系统参数设置例如min_free_kbytes 和 zone_reclaim_mode然而并不能消除 CPU 毛刺问题。通过与社区朋友的会诊讨论内核版本 2.6 操作系统内存回收存在 Bug。我们决定更换集群的操作系统。解决办法将集群的 CentOS 6 升级到 CentOS 7内核版本也从 2.6 升级到了 3.10升级后 CPU 毛刺问题不在乎出现。升级方式采取的方式先扩容后缩容先把 CentOS 7 的节点加入集群后再将 CentOS 6 的节点移除详见前面实战部分“RocketMQ 集群平滑运维”。Linux version 3.10.0-1062.4.1.el7.x86_64 (mockbuildkbuilder.bsys.centos.org) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-39) (GCC) ) #1 SMP Fri Oct 18 17:15:30 UTC 2019集群频繁抖动发送超时现象描述监控和业务同学反馈发送超时而且频繁出现。具体现象如下图。预热现象说明上图分别为开启预热时warmMapedFileEnabletrue集群的发送 RT 监控、Broker 开启预热设置时的日志。内存传输现象说明上图分别为开启堆外内存传输transferMsgByHeapfalse时的 CPU 抖动截图、系统内存分配不足截图、Broker 日志截图。原因分析上面展现的两种显现均会导致集群 CPU 抖动、客户端发送超时对业务造成影响。预热设置在预热文件时会填充 1 个 G 的假值 0 作为占位符提前分配物理内存防止消息写入时发生缺页异常。然而往往伴随着磁盘写入耗时过长、CPU 小幅抖动、业务具体表现为发送耗时过长超时错误增多。关闭预热配置从集群 TPS 摸高情况来看并未有明显的差异但是从稳定性角度关闭却很有必要。堆外内存transferMsgByHeap 设置为 false 时通过堆外内存传输数据相比堆内存传输减少了数据拷贝、零字节拷贝、效率更高。但是可能造成堆外内存分配不够触发系统内存回收和落盘操作设置为 true 时运行更加平稳。解决办法预热 warmMapedFileEnable 默认为 false保持默认即可。如果开启了可以通过热更新关闭。bin/mqadmin updateBrokerConfig -b x.x.x.x:10911 -n x.x.x.x:9876 -k warmMapedFileEnable -v false内存传输参数 transferMsgByHeap 默认为 true即通过堆内内存传输保持默认即可。如果关闭了可以通过热更新开启。bin/mqadmin updateBrokerConfig -b x.x.x.x:10911 -n x.x.x.x:9876 -k transferMsgByHeap -v true用了此属性消费性能下降一半现象描述配置均采用 8C16GRocketMQ 的消费线程 20 个通过测试消费性能在 1.5 万 tps 左右。通过 tcpdump 显示在消费的机器存在频繁的域名解析过程10.x.x.185 向 DNS 服务器 100.x.x.136.domain 和 10.x.x.138.domain 请求解析。而 10.x.x.185 这台机器又是消息发送者的机器 IP测试的发送和消费分别部署在两台机器上。问题消费时为何会有消息发送方的 IP 呢而且该 IP 还不断进行域名解析。原因分析通过 dump 线程堆栈如下图代码定位在消费时有通过 MessageExt.bornHost.getBornHostNameString 获取消费这信息。public class MessageExt extends Message { private static final long serialVersionUID 5720810158625748049L; private int queueId; private int storeSize; private long queueOffset; private int sysFlag; private long bornTimestamp; private SocketAddress bornHost; private long storeTimestamp; private SocketAddress storeHost; private String msgId; private long commitLogOffset; private int bodyCRC; private int reconsumeTimes; private long preparedTransactionOffset; }调用 GetBornHostNameString 获取 HostName 时会根据 IP 反查 DNS 服务器InetSocketAddress inetSocketAddress (InetSocketAddress)this.bornHost; return inetSocketAddress.getAddress().getHostName();解决办法消费的时候不要使用 MessageExt.bornHost.getBornHostNameString 即可去掉该属性配置 8C16G 的机器消费性能在 3 万 TPS提升了 1 倍。