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https://issues.apache.org/jira/browse/CLOUDSTACK-9595?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15664293#comment-15664293
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ASF GitHub Bot commented on CLOUDSTACK-9595:
--------------------------------------------
Github user jburwell commented on the issue:
https://github.com/apache/cloudstack/pull/1762
@yvsubhash according to the (MySQL deadlock
documenation)[http://dev.mysql.com/doc/refman/5.7/en/innodb-deadlocks.html], a
`MYSQL_DEADLOCK_ERROR_CODE` error indicates the enclosing transaction has been
rolled back. The proper handling for this error is to re-execute all
statements executed in the aborted transaction. From a best practices
perspective, all base data should be re-retrieved and changed to ensure logical
consistency with changes made by the transaction that won deadlock resolution.
As I understand this patch, only the most recently executed DML is retried.
Therefore, any previously executed changes will be discarded and the DML will
be re-executed either in a new transaction or in auto-commit (I didn't look up
how the client handles the transaction context in this scenario). If my
understanding is correct, this patch could lead to issues ranging from
unexpected foreign key integrity errors to data corruption.
Rather attempting to implement a generic retry, I think the best approach
to addressing deadlocks is to treat them bugs. This patch could be modified to
provide detailed logging information about the conditions under which a
deadlock occurs providing the information necessary to refactor the system to
avoid lock contention.
> Transactions are not getting retried in case of database deadlock errors
> ------------------------------------------------------------------------
>
> Key: CLOUDSTACK-9595
> URL: https://issues.apache.org/jira/browse/CLOUDSTACK-9595
> Project: CloudStack
> Issue Type: Bug
> Security Level: Public(Anyone can view this level - this is the
> default.)
> Affects Versions: 4.8.0
> Reporter: subhash yedugundla
> Fix For: 4.8.1
>
>
> Customer is seeing occasional error 'Deadlock found when trying to get lock;
> try restarting transaction' messages in their management server logs. It
> happens regularly at least once a day. The following is the error seen
> 2015-12-09 19:23:19,450 ERROR [cloud.api.ApiServer]
> (catalina-exec-3:ctx-f05c58fc ctx-39c17156 ctx-7becdf6e) unhandled exception
> executing api command: [Ljava.lang.String;@230a6e7f
> com.cloud.utils.exception.CloudRuntimeException: DB Exception on:
> com.mysql.jdbc.JDBC4PreparedStatement@74f134e3: DELETE FROM
> instance_group_vm_map WHERE instance_group_vm_map.instance_id = 941374
> at com.cloud.utils.db.GenericDaoBase.expunge(GenericDaoBase.java:1209)
> at sun.reflect.GeneratedMethodAccessor360.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at
> org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
> at
> com.cloud.utils.db.TransactionContextInterceptor.invoke(TransactionContextInterceptor.java:34)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:161)
> at
> org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
> at
> org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
> at com.sun.proxy.$Proxy237.expunge(Unknown Source)
> at
> com.cloud.vm.UserVmManagerImpl$2.doInTransactionWithoutResult(UserVmManagerImpl.java:2593)
> at
> com.cloud.utils.db.TransactionCallbackNoReturn.doInTransaction(TransactionCallbackNoReturn.java:25)
> at com.cloud.utils.db.Transaction$2.doInTransaction(Transaction.java:57)
> at com.cloud.utils.db.Transaction.execute(Transaction.java:45)
> at com.cloud.utils.db.Transaction.execute(Transaction.java:54)
> at
> com.cloud.vm.UserVmManagerImpl.addInstanceToGroup(UserVmManagerImpl.java:2575)
> at
> com.cloud.vm.UserVmManagerImpl.updateVirtualMachine(UserVmManagerImpl.java:2332)
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