MySQL案例03：（MyCAT报错） [ERROR][$_NIOREACTOR-3-RW] caught err: java.lang.OutOfM emoryError: Unable to acquire 131072 bytes of memory, got 0

上班坐下来没多久，接同事电话说有两台mysql服务器无法访问，其中这两台服务器是mycat服务器+MySQL服务器，具体处理过程如下：

一、错误信息

错误信息01：

INFO   | jvm 3    | 2018/05/10 10:00:54 | 2018-05-10 10:00:54,406 [INFO ][$_NIOREACTOR-3-RW] close connection,reason:Bad:
java.lang.OutOfMemoryError: Unable to acquire 131072 bytes of memory, got 0 ,MySQLConnection [id=6173, lastTime=1525917654
250, user=username, schema=database10, old shema=database10, borrowed=true, fromSlaveDB=true, threadId=42067, charset=utf8, txIsolation=3,
 autocommit=true, attachment=dn10{SELECT *
INFO   | jvm 3    | 2018/05/10 10:00:54 | FROM cu_link
INFO   | jvm 3    | 2018/05/10 10:00:54 | WHERE (customer_id = 1964
INFO   | jvm 3    | 2018/05/10 10:00:54 |               OR customer_link_id = )
INFO   | jvm 3    | 2018/05/10 10:00:54 |       AND state = 1
INFO   | jvm 3    | 2018/05/10 10:00:54 |       AND company_id = '3BD'
INFO   | jvm 3    | 2018/05/10 10:00:54 | LIMIT 100000000}, respHandler=io.mycat.backend.mysql.nio.handler.MultiNodeQueryH
andler@530d01dc, host=xx.xx.xx.xx, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]  (io.mycat.net.
AbstractConnection:AbstractConnection.java:508)
INFO   | jvm 3    | 2018/05/10 10:00:54 | 2018-05-10 10:00:54,407 [ERROR][$_NIOREACTOR-3-RW] caught err:  java.lang.OutOfM
emoryError: Unable to acquire 131072 bytes of memory, got 0
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.memory.unsafe.memory.mm.MemoryConsumer.allocateLongArray(Memor
yConsumer.java:92)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.memory.unsafe.utils.sort.UnsafeInMemorySorter.<init>(UnsafeInM
emorySorter.java:114)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.memory.unsafe.utils.sort.UnsafeExternalSorter.<init>(UnsafeExt
ernalSorter.java:131)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.memory.unsafe.utils.sort.UnsafeExternalSorter.create(UnsafeExt
ernalSorter.java:98)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.memory.unsafe.utils.sort.UnsafeExternalRowSorter.<init>(Unsafe
ExternalRowSorter.java:64)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.sqlengine.mpp.DataNodeMergeManager.onRowMetaData(DataNodeMerge
Manager.java:249)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.backend.mysql.nio.handler.MultiNodeQueryHandler.fieldEofRespon
se(MultiNodeQueryHandler.java:643)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.backend.mysql.nio.MySQLConnectionHandler.handleFieldEofPacket(
MySQLConnectionHandler.java:192)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.backend.mysql.nio.MySQLConnectionHandler.handleData(MySQLConne
ctionHandler.java:118)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.net.handler.BackendAsyncHandler.offerData(BackendAsyncHandler.
java:36)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.backend.mysql.nio.MySQLConnectionHandler.handle(MySQLConnectio
nHandler.java:80)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.net.AbstractConnection.handle(AbstractConnection.java:263)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.net.AbstractConnection.onReadData(AbstractConnection.java:321)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.net.NIOSocketWR.asynRead(NIOSocketWR.java:190)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.net.AbstractConnection.asynRead(AbstractConnection.java:273)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at io.mycat.net.NIOReactor$RW.run(NIOReactor.java:102)
INFO   | jvm 3    | 2018/05/10 10:00:54 |       at java.lang.Thread.run(Thread.java:745)
INFO   | jvm 3    | 2018/05/10 10:00:54 |      (io.mycat.net.NIOReactor$RW:NIOReactor.java:132) 

错误信息02：

LIMIT 100000000}, packetId=1], host=xx.xx.xx.xx, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false] frontend host:x.x.x.x/49657/username
2018-05-10 10:25:39.883  WARN [$_NIOREACTOR-2-RW] (io.mycat.backend.mysql.nio.handler.SingleNodeHandler.backConnectionErr(SingleNodeHandler.java:249)) - execute  sql err : errno:1146 Table 'cr.vacode' doesn't exist con:MySQLConnection [id=89, lastTime=1525919139870, user=username, schema=cr, old shema=cr, borrowed=true, fromSlaveDB=true, threadId=553442, charset=utf8, txIsolation=3, autocommit=true, attachment=dn00{SELECT *
FROM vaCode
ORDER BY id DESC

错误信息03：

java.sql.SQLNonTransientException:  find no Route:SELECT * FROM `database03`.`cain` LIMIT 0

二、错误原因

1、针对错误信息01，基本可以断定是由于服务器jvm设置不当，导致内存溢出。

2、针对错误信息02，基本可以断定是由于在数据库服务器新增表，没有配置在mycat中或由于MyCAT大小写配置和数据库服务器表名大小写配置有关

3、针对错误信息03，基本可以断定路由问题

三、解决方案

1、查看系统内存

[root@localhost ~]# free -g
             total       used       free     shared    buffers     cached
Mem:            15         15          0          5          0          6
-/+ buffers/cache:          8          6
Swap:            7          5          2

2、查看系统日志

[root@localhost logs]#vi /var/log/message

如果是OOM的话，系统日志会记录的。

3、查看数据库日志和mycat日志

[root@localhost logs]#vi /home/mysql/err.log

[root@localhost logs]# vi /usr/local/mycat/logs/mycat.log
[root@localhost logs]# [root@localhost logs]# vi /usr/local/mycat/logs/wrapper.log

4、查看监控情况

通过zabbix查看系统CPU、内存、SWAP使用情况

5、查看具体进程对应资源消耗

[root@localhost ~]# top -p 31665

[root@localhost ~]# top -p 30388

通过ps 查看系统进程的时候和top查看资源消耗的时候，发现居然还跑着oracle进程，而且其sga设置为8G，PGA设置的是2G

这里看到实际设置的最大应用内存(21G+)已经超过了物理内存的实际最大值（15G）,而写看到系统已经使用了swap分区（虽然现在看着还有7G左右的cache），说明

6、查看mycat的进程运行内存

下面的最大堆内存4G（具体使用情况可以通过jmap查看），单线程内存最大64M，最大的nio内存2G（DirectMemory是java nio引入的，直接以native的方式分配内存，不受jvm管理）

查看其具体配置文件

[root@localhost mycat]# more /usr/local/mycat/conf/wrapper.conf

# Java Additional Parameters
#wrapper.java.additional.1=
wrapper.java.additional.1=-DMYCAT_HOME=.
wrapper.java.additional.2=-server
wrapper.java.additional.3=-XX:MaxPermSize=64M
wrapper.java.additional.4=-XX:+AggressiveOpts
wrapper.java.additional.5=-XX:MaxDirectMemorySize=2G
wrapper.java.additional.6=-Dcom.sun.management.jmxremote
wrapper.java.additional.7=-Dcom.sun.management.jmxremote.port=1984
wrapper.java.additional.8=-Dcom.sun.management.jmxremote.authenticate=false
wrapper.java.additional.9=-Dcom.sun.management.jmxremote.ssl=false
wrapper.java.additional.10=-Xmx4G
wrapper.java.additional.11=-Xms1G

# Initial Java Heap Size (in MB)
#wrapper.java.initmemory=3

# Maximum Java Heap Size (in MB)
#wrapper.java.maxmemory=64

# Application parameters.  Add parameters as needed starting from 1
wrapper.app.parameter.1=io.mycat.MycatStartup
wrapper.app.parameter.2=start

这里看内存设置还是正常范围内

7、最终解决方案

（由于开发联系我时，我测试数据库服务、MyCAT服务均正常，所以具体排查过程大致如上，后经与开发沟通，他们说是磁盘空间不足导致的，清理磁盘重启mycat问题解决）

8、资源统计

[root@localhost logs]# dstat -lrmc --top-io --top-mem --top-cpu
Terminal width too small, trimming output.
---load-avg--- --io/total- ------memory-usage----- ----total-cpu-usage---- ----most-expensive---- --most-expensive->
 1m   5m  15m | read  writ| used  buff  cach  free|usr sys idl wai hiq siq|     i/o process      |  memory process >
0.86 0.56 0.47|76.7   105 |8825M 7816k 6938M  181M|  4   1  92   3   0   0|init         16M  477k|mysqld      5789M>
0.86 0.56 0.47|1083   177 |8835M 7828k 6928M  181M| 30   4  47  19   0   1|mysqld      416k 4354k|mysqld      5789M>