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POCommunicationsException: Communications link failure
 

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  1. POCommunicationsException: Communications link failure
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    <p>I used java to query some records from Mysql. But in some querys of one duration, i meet a problem which make query failed, but in others , it query successful. The error message is next: </p> <pre><code>com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure The last packet successfully received from the server was 90 milliseconds ago. The last packet sent successfully to the server was 1,674 milliseconds ago. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3090) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2979) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3520) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:935) at com.mysql.jdbc.MysqlIO.nextRow(MysqlIO.java:1433) at com.mysql.jdbc.MysqlIO.readSingleRowSet(MysqlIO.java:2924) at com.mysql.jdbc.MysqlIO.getResultSet(MysqlIO.java:477) at com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:2619) at com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:1788) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2209) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2619) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2569) at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1521) ...... at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58) Caused by: java.io.IOException: Packets received out of order at com.mysql.jdbc.MysqlIO.readRemainingMultiPackets(MysqlIO.java:3152) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3077) ... 23 more </code></pre> <p>I have tried some method, such like:</p> <ul> <li>set <code>max_allowed_packet = 128 * 1024 * 1024</code> in <code>/etc/my.conf</code> </li> <li>add <code>?autoReconnect=true&amp;failOverReadOnly=false&amp;maxReconnects=10</code> to my connection url</li> </ul> <p>but nothing happens.</p> <p>My environments is:</p> <ul> <li>Mysql: 5.5.3-m3-log Source distribution</li> <li>Java: 1.6.0_16</li> <li>Jdk: HotSpot(TM) 64-Bit Server VM (build 14.2-b01, mixed mode)</li> <li>JDBC: mysql-connector-java-5.1.18</li> </ul>
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    1. COIn the operation, i used `group_concat` and my concat string is very long. And i also try the query using php, it works well. When i set `group_concat_max_len` < 32M, it will cut some data by was cut by GROUP_CONCAT() and return success. But if group_concat_max_len > 32M, it failed.
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    2. COpossible duplicate of [MySQL-JDBC: Communications Link Failure](http://stackoverflow.com/questions/2121829/mysql-jdbc-communications-link-failure)
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