记一次Maxwell出现Communications link failure

原报错信息：

connecting to jdbc:mysql://hadoop01:3306/maxwell?allowPublicKeyRetrieval=true&connectTimeout=5000&serverTimezone=Asia%2FShanghai&zeroDateTimeBehavior=convertToNull&useSSL=false
30954 [WARN] BasicResourcePool: com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@14caeb55 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:448) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1176) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1163) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1908) [c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696) [mchange-commons-java-0.2.19.jar:0.2.19]
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at sun.reflect.GeneratedConstructorAccessor24.newInstance(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.8.0_212]
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[?:1.8.0_212]
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:378) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeAuthenticationProvider.connect(NativeAuthenticationProvider.java:205) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1433) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.NativeSession.connect(NativeSession.java:133) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:948) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:818) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	... 12 more
Caused by: javax.net.ssl.SSLException: Unsupported record version Unknown-0.0
	at sun.security.ssl.InputRecord.checkRecordVersion(InputRecord.java:552) ~[?:1.8.0_212]
	at sun.security.ssl.InputRecord.readV3Record(InputRecord.java:565) ~[?:1.8.0_212]
	at sun.security.ssl.InputRecord.read(InputRecord.java:529) ~[?:1.8.0_212]
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:975) ~[?:1.8.0_212]
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1367) ~[?:1.8.0_212]
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1395) ~[?:1.8.0_212]
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1379) ~[?:1.8.0_212]
	at com.mysql.cj.protocol.ExportControlled.performTlsHandshake(ExportControlled.java:347) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.StandardSocketFactory.performTlsHandshake(StandardSocketFactory.java:191) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeSocketConnection.performTlsHandshake(NativeSocketConnection.java:101) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:369) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeAuthenticationProvider.connect(NativeAuthenticationProvider.java:205) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1433) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.NativeSession.connect(NativeSession.java:133) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:948) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:818) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	... 12 more
30948 [WARN] BasicResourcePool: com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@5f4cd657 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:448) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1176) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1163) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44) ~[c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1908) [c3p0-0.9.5.5.jar:0.9.5.5]
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696) [mchange-commons-java-0.2.19.jar:0.2.19]
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at sun.reflect.GeneratedConstructorAccessor24.newInstance(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.8.0_212]
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[?:1.8.0_212]
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:378) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeAuthenticationProvider.connect(NativeAuthenticationProvider.java:205) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1433) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.NativeSession.connect(NativeSession.java:133) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:948) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:818) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	... 12 more
Caused by: javax.net.ssl.SSLException: Unsupported record version Unknown-0.0
	at sun.security.ssl.InputRecord.checkRecordVersion(InputRecord.java:552) ~[?:1.8.0_212]
	at sun.security.ssl.InputRecord.readV3Record(InputRecord.java:565) ~[?:1.8.0_212]
	at sun.security.ssl.InputRecord.read(InputRecord.java:529) ~[?:1.8.0_212]
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:975) ~[?:1.8.0_212]
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1367) ~[?:1.8.0_212]
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1395) ~[?:1.8.0_212]
	at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1379) ~[?:1.8.0_212]
	at com.mysql.cj.protocol.ExportControlled.performTlsHandshake(ExportControlled.java:347) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.StandardSocketFactory.performTlsHandshake(StandardSocketFactory.java:191) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeSocketConnection.performTlsHandshake(NativeSocketConnection.java:101) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeProtocol.negotiateSSLConnection(NativeProtocol.java:369) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeAuthenticationProvider.connect(NativeAuthenticationProvider.java:205) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1433) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.NativeSession.connect(NativeSession.java:133) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:948) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:818) ~[mysql-connector-j-8.0.31.jar:8.0.31]
	... 12 more
30949 [WARN] BasicResourcePool: com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@46456c0 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

很直观的可以看出来连接不上MySQL

遇见这类问题可以依次排查

1、确认数据库服务器是否正在运行，并且网络连接是正常的。

2、如果数据库服务器正在运行并且网络连接良好，请检查防火墙设置，确保端口号正确开放。

3、确认数据库连接URL、用户名、密码等参数是否正确。

4、如果以上步骤都没有解决问题，可以尝试使用数据库提供商的官方驱动程序来替换当前的驱动程序，或者升级现有的驱动程序版本。

但是该报错很明显就是驱动的问题，省略前3步，直接更换适配的驱动。

解决：

cd 进入Maxwell的lib目录

更换新驱动

cp /opt/software/mysql-connector-java-5.1.27-bin.jar ./

解决该问题