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https://issues.apache.org/jira/browse/DBCP-400?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13721099#comment-13721099
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Phil Steitz commented on DBCP-400:
----------------------------------
Thanks for reporting this. You are correct, the documentation should say that
negative values indicate no limit.
We should make sure to fix all javadoc as well. In several cases, we
incorrectly (and non-standardly) use the term "non-positive" when we mean
"negative."
> The documentation of maxOpenPreparedStatements parameter seems to be wrong
> --------------------------------------------------------------------------
>
> Key: DBCP-400
> URL: https://issues.apache.org/jira/browse/DBCP-400
> Project: Commons Dbcp
> Issue Type: Bug
> Affects Versions: 1.4, 1.4.1
> Reporter: Gábor Lipták
> Labels: limit, pool
>
> We had earlier a datasource, which had no maxOpenPreparedStatements property
> defined. Something like this:
> {code:xml}
> <bean id="basicDataSource" class="org.apache.commons.dbcp.BasicDataSource"
> init-method="createDataSource" destroy-method="close">
> <property name="poolPreparedStatements" value="true" />
> <property name="url" value="${datasource.url}" />
> <property name="driverClassName"
> value="${datasource.driverClassName}" />
> <property name="username" value="${datasource.username}" />
> <property name="password" value="${datasource.password}" />
> <property name="initialSize" value="${datasource.initialSize}"
> />
> <property name="maxActive" value="${datasource.maxActive}" />
> <property name="maxIdle" value="${datasource.maxIdle}" />
> <property name="minIdle" value="${datasource.minIdle}" />
> <property name="timeBetweenEvictionRunsMillis"
> value="${datasource.timeBetweenEvictionRunsMillis}" />
> <property name="minEvictableIdleTimeMillis"
> value="${datasource.minEvictableIdleTimeMillis}" />
> <property name="maxWait" value="${datasource.maxWait}" />
> </bean>
> {code}
> Then we wanted to have a parameter to limit the prepared statement pool, so
> we added a new line for the maxOpenPreparedStatements (for compatibility
> reasons we added the line with a config file having '0' value which should
> mean unlimited according to the documentation at
> http://commons.apache.org/proper/commons-dbcp/configuration.html):
> {code:xml}
> <bean id="basicDataSource" class="org.apache.commons.dbcp.BasicDataSource"
> init-method="createDataSource" destroy-method="close">
> <property name="poolPreparedStatements" value="true" />
> <property name="maxOpenPreparedStatements"
> value="${datasource.maxOpenPreparedStatements}" />
> <property name="url" value="${datasource.url}" />
> <property name="driverClassName"
> value="${datasource.driverClassName}" />
> <property name="username" value="${datasource.username}" />
> <property name="password" value="${datasource.password}" />
> <property name="initialSize" value="${datasource.initialSize}"
> />
> <property name="maxActive" value="${datasource.maxActive}" />
> <property name="maxIdle" value="${datasource.maxIdle}" />
> <property name="minIdle" value="${datasource.minIdle}" />
> <property name="timeBetweenEvictionRunsMillis"
> value="${datasource.timeBetweenEvictionRunsMillis}" />
> <property name="minEvictableIdleTimeMillis"
> value="${datasource.minEvictableIdleTimeMillis}" />
> <property name="maxWait" value="${datasource.maxWait}" />
> </bean>
> {code}
> We ended up in having the following exception:
> {noformat}
> Caused by: java.sql.SQLException: MaxOpenPreparedStatements limit reached
> at
> org.apache.commons.dbcp.PoolingConnection.prepareStatement(PoolingConnection.java:109)
> at
> org.apache.commons.dbcp.DelegatingConnection.prepareStatement(DelegatingConnection.java:281)
> at
> org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.prepareStatement(PoolingDataSource.java:313)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> ...
> ...
> [:1.7.0_07]
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)[:1.7.0_07]
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)[:1.7.0_07]
> at java.lang.reflect.Method.invoke(Method.java:601)[:1.7.0_07]
> at
> org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:309)
> at
> org.springframework.osgi.service.importer.support.internal.aop.ServiceInvoker.doInvoke(ServiceInvoker.java:58)
> at
> org.springframework.osgi.service.importer.support.internal.aop.ServiceInvoker.invoke(ServiceInvoker.java:62)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
> at
> org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:131)
> at
> org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:119)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
> at
> org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor$1.run(ServiceTCCLInterceptor.java:47)
> at
> org.springframework.osgi.util.internal.PrivilegedUtils.executeWithCustomTCCL(PrivilegedUtils.java:124)[80:org.springframework.osgi.core:1.2.1]
> at
> org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor.invokePrivileged(ServiceTCCLInterceptor.java:44)
> at
> org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor.invoke(ServiceTCCLInterceptor.java:36)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
> at
> org.springframework.osgi.service.importer.support.LocalBundleContextAdvice.invoke(LocalBundleContextAdvice.java:59)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
> at
> org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:131)
> at
> org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:119)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
> at
> org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
> at $Proxy69.getSpecializedSequenceProvider(Unknown Source)
> at ...)
> ... 36 more
> Caused by: java.util.NoSuchElementException: Pool exhausted
> at
> org.apache.commons.pool.impl.GenericKeyedObjectPool.borrowObject(GenericKeyedObjectPool.java:1143)
> at
> org.apache.commons.dbcp.PoolingConnection.prepareStatement(PoolingConnection.java:107)
> ... 67 more
> {noformat}
> So it turned out, that the documentation is wrong. Only negative numbers like
> -1 mean unlimited. 0 seems to mean limited to one item. Please correct the
> documentation to avoid problems of others.
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