Gábor Lipták created DBCP-400:
---------------------------------
Summary: 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
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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