Nota: so di thread this ma è piuttosto vecchio e inoltre, la soluzione non ha funzionato per me.Pool di connessione JDBC compatibile con App Engine
Sto utilizzando App Engine insieme a Cloud SQL e vorrei condividere un pool di connessioni aperte tra tutti gli utenti correnti dell'applicazione. Ho provato diverse implementazioni di pool di connessioni e funzionano tutte perfettamente con il server di sviluppo locale, tuttavia, quando vengono implementate nel cloud, falliscono. Suppongo che la ragione sia l'ambiente "sandbox" ristretto di App Engine. Qualcuno sa del pool di connessioni JDBC che funziona su App Engine?
Apache Commons DBCP
...
Caused by: java.lang.NoClassDefFoundError: Could not initialize class org.apache.commons.dbcp2.PoolableConnection
at com.google.appengine.runtime.Request.process-a49d46300800d0ca(Request.java)
at org.apache.commons.dbcp2.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:254)
at org.apache.commons.dbcp2.BasicDataSource.validateConnectionFactory(BasicDataSource.java:2162)
at org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:2148)
at org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:1903)
at org.apache.commons.dbcp2.BasicDataSource$PaGetConnection.run(BasicDataSource.java:2267)
at org.apache.commons.dbcp2.BasicDataSource$PaGetConnection.run(BasicDataSource.java:2263)
at java.security.AccessController.doPrivileged(AccessController.java:63)
at org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1404)
...
Tomcat JDBC Connection Pool
...
Caused by: java.lang.SecurityException: Unable to get members for class org.apache.tomcat.jdbc.pool.DataSource
...
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
... 45 more
Caused by: java.lang.NoClassDefFoundError: javax/management/MalformedObjectNameException
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2517)
... 45 more
Caused by: java.lang.ClassNotFoundException: javax.management.MalformedObjectNameException
... 45 more
HikariCP
...
java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup")
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:375)
at java.security.AccessController.checkPermission(AccessController.java:565)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
at java.lang.Thread.init(Thread.java:378)
at java.lang.Thread.<init>(Thread.java:527)
at com.zaxxer.hikari.util.DefaultThreadFactory.newThread(DefaultThreadFactory.java:32)
at java.util.concurrent.ThreadPoolExecutor$Worker.<init>(ThreadPoolExecutor.java:591)
at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:922)
at java.util.concurrent.ThreadPoolExecutor.ensurePrestart(ThreadPoolExecutor.java:1591)
at java.util.concurrent.ScheduledThreadPoolExecutor.delayedExecute(ScheduledThreadPoolExecutor.java:305)
at java.util.concurrent.ScheduledThreadPoolExecutor.scheduleAtFixedRate(ScheduledThreadPoolExecutor.java:542)
at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:161)
at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:114)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:102)
...
Vibur DBCP
...
Caused by: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup")
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:375)
at java.security.AccessController.checkPermission(AccessController.java:565)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
at java.lang.Thread.init(Thread.java:378)
at java.lang.Thread.<init>(Thread.java:448)
at org.vibur.objectpool.reducer.SamplingPoolReducer.<init>(SamplingPoolReducer.java:78)
at org.vibur.dbcp.pool.PoolOperations$PoolReducer.<init>(PoolOperations.java:88)
at org.vibur.dbcp.pool.PoolOperations$PoolReducer.<init>(PoolOperations.java:86)
at org.vibur.dbcp.pool.PoolOperations.<init>(PoolOperations.java:79)
at org.vibur.dbcp.ViburDBCPDataSource.start(ViburDBCPDataSource.java:197)
....
c3p0
...
Caused by: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup")
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:375)
at java.security.AccessController.checkPermission(AccessController.java:565)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
at java.lang.Thread.init(Thread.java:378)
at java.lang.Thread.<init>(Thread.java:487)
...
visto su alcune altre questioni che StackOverflow HikariCP supporta personalizzato ThreadManager, in modo da poter creare discussioni con ThreadManager whitelist di GAE. –