我有一个应用程序连接到单个Google Cloud SQL实例中的多个数据库。根据下拉选择，GAE应用程序将从5个数据库中选择一个记录。
问题在于，当我选择前4个数据库（在下拉列表中没有特定顺序）时，GAE应用程序成功连接到数据库并能够检索记录。但是当我从下拉列表中选择第五个数据库时，会抛出一个错误。错误和堆栈跟踪如下。它不是特定数据库的错误，因为错误不依赖于选择了哪个数据库的顺序。选择的最后一个或第五个数据库，无关紧要，始终以相同的错误消息失败。
任何建议都将非常感谢。
InspectAPI.java：
public Element[] getComponentsList(@Named("province")String provinceName, User user) throws Exception {
if (user == null) {
throw new UnauthorizedException("API calls must be authenticated.");
}
if (!AuthorizationService.hasAnyOrRoles(user.getEmail(), AuthorizationService.ROLE_ALL_ROLES)
|| !AuthorizationService.hasProvincieAccess(user.getEmail(), provinceName)) {
throw new UnauthorizedException("You are not authorized to invoke this API method.");
}
EntityManager em = null;
Element[] e = null;
try {
em = EMF.getFStore().createEntityManager();
em.getTransaction().begin();
e = (ElementRubrieken[]) em.createQuery("SELECT i FROM Element i").getResultList()
.toArray(new Element[0]);
} catch (NoResultException nre) {
// no result
if (e == null) {
return e;
}
} catch (Exception ex) {
log.log(Level.SEVERE, "Unable to get inspections.", ex);
throw new InternalServerErrorException("Unable to get inspections.");
} finally {
if (em != null) {
em.getTransaction().commit();
em.close();
}
}
return e;
}
EMF.java
public static EntityManagerFactory getFicheStore() {
if (emfFicheInstance == null) {
Map<String, String> properties = new HashMap<String, String>();
if (SystemProperty.environment.value() == SystemProperty.Environment.Value.Production) {
properties.put("javax.persistence.jdbc.driver", "com.mysql.jdbc.GoogleDriver");
properties.put("javax.persistence.jdbc.url", System.getProperty("cloudsql.prod.f.url"));
properties.put("javax.persistence.jdbc.user", System.getProperty("cloudsql.prod.f.user"));
properties.put("javax.persistence.jdbc.password", System.getProperty("cloudsql.prod.f.password"));
properties.put("javax.persistence.jdbc.db", System.getProperty("cloudsql.prod.f.db"));
} else {
properties.put("javax.persistence.jdbc.driver", "com.mysql.jdbc.Driver");
properties.put("javax.persistence.jdbc.url", System.getProperty("cloudsql.dev.f.url"));
properties.put("javax.persistence.jdbc.user", System.getProperty("cloudsql.dev.f.user"));
properties.put("javax.persistence.jdbc.password", System.getProperty("cloudsql.dev.f.password"));
properties.put("javax.persistence.jdbc.db", System.getProperty("cloudsql.dev.f.db"));
}
emfFicheInstance = Persistence.createEntityManagerFactory(
System.getProperty("com.myproject.services.emfFactory.persistenceUnitName"),
properties);
}
return emfFicheInstance;
}
错误和堆栈跟踪：
E 00:42:39.184 com.myproject.api.InspectAPI getComponentsList: Unable to get inspections.
javax.persistence.PersistenceException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at org.datanucleus.api.jpa.NucleusJPAHelper.getJPAExceptionForNucleusException(NucleusJPAHelper.java:270)
at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:202)
at com.myproject.api.InspectAPI.getComponentsList(InspectAPI.java:223)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_$1.run(Method_.java:179)
at java.security.AccessController.doPrivileged(Native Method)
at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_.privilegedInvoke(Method_.java:176)
at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_.invoke_(Method_.java:137)
at com.google.apphosting.runtime.security.shared.intercept.java.lang.reflect.Method_.invoke(Method_.java:45)
at com.google.api.server.spi.SystemService.invokeServiceMethod(SystemService.java:359)
at com.google.api.server.spi.SystemServiceServlet.execute(SystemServiceServlet.java:160)
at com.google.api.server.spi.SystemServiceServlet.doPost(SystemServiceServlet.java:118)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:254)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:146)
at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:484)
at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:438)
at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:445)
at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:220)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:309)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:301)
at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:442)
at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
at java.lang.Thread.run(Thread.java:724)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:46)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:350)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2416)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2450)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2235)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:818)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:46)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:404)
at com.mysql.jdbc.GoogleNonRegisteringDriver$JdbcWrapper.getInstance(GoogleNonRegisteringDriver.java:276)
at com.mysql.jdbc.GoogleNonRegisteringDriver.connect(GoogleNonRegisteringDriver.java:246)
at java.sql.DriverManager.getConnection(DriverManager.java:571)
at java.sql.DriverManager.getConnection(DriverManager.java:187)
at org.datanucleus.store.rdbms.datasource.dbcp.DriverManagerConnectionFactory.createConnection(DriverManagerConnectionFactory.java:78)
at org.datanucleus.store.rdbms.datasource.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:582)
at org.datanucleus.store.rdbms.datasource.dbcp.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1158)
at org.datanucleus.store.rdbms.datasource.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:108)
at org.datanucleus.store.rdbms.ConnectionProviderPriorityList.getConnection(ConnectionProviderPriorityList.java:57)
at org.datanucleus.store.rdbms.ConnectionFactoryImpl$ManagedConnectionImpl.getConnection(ConnectionFactoryImpl.java:354)
at org.datanucleus.store.rdbms.ConnectionFactoryImpl$ManagedConnectionImpl.getXAResource(ConnectionFactoryImpl.java:314)
at org.datanucleus.store.connection.ConnectionManagerImpl.enlistResource(ConnectionManagerImpl.java:354)
at org.datanucleus.store.connection.ConnectionManagerImpl.allocateConnection(ConnectionManagerImpl.java:226)
at org.datanucleus.store.connection.AbstractConnectionFactory.getConnection(AbstractConnectionFactory.java:60)
at org.datanucleus.store.AbstractStoreManager.getConnection(AbstractStoreManager.java:432)
at org.datanucleus.store.AbstractStoreManager.getConnection(AbstractStoreManager.java:401)
at org.datanucleus.store.rdbms.query.JPQLQuery.performExecute(JPQLQuery.java:512)
at org.datanucleus.store.query.Query.executeQuery(Query.java:1789)
at org.datanucleus.store.query.Query.executeWithMap(Query.java:1693)
at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:185)
<continued in next message>
E 00:42:39.184 <continued from previous message>
at com.myproject.api.InspectAPI.getComponentsList(InspectAPI.java:223)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:45)
at com.google.api.server.spi.SystemService.invokeServiceMethod(SystemService.java:359)
at com.google.api.server.spi.SystemServiceServlet.execute(SystemServiceServlet.java:160)
at com.google.api.server.spi.SystemServiceServlet.doPost(SystemServiceServlet.java:118)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:438)
at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:445)
at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:220)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:309)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:301)
at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:442)
... 1 more
Caused by: java.net.SocketException: Unable to open connection to the instance: myproject-tst:mysql
at com.mysql.jdbc.GoogleCloudSqlSocket.<init>(GoogleCloudSqlSocket.java:48)
at com.mysql.jdbc.GoogleCloudSqlSocketFactory.connect(GoogleCloudSqlSocketFactory.java:81)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:300)
... 64 more
Caused by: java.io.FileNotFoundException: /cloudsql/myproject-tst:mysql (No such file or directory)
at java.io.RandomAccessFile.open(Native Method)
at java.io.RandomAccessFile.<init>(RandomAccessFile.java:247)
at java.io.RandomAccessFile.<init>(RandomAccessFile.java:132)
at com.mysql.jdbc.GoogleCloudSqlSocket$RandomAccessFileHelper.getFile(GoogleCloudSqlSocket.java:249)
at com.mysql.jdbc.GoogleCloudSqlSocket.<init>(GoogleCloudSqlSocket.java:46)
... 66 more
答案 0 :(得分：0)
我看到这个错误的两个原因：
您正在达到此处描述的12个并发连接的限制[1]。出于某种原因，您可能没有正确关闭连接。
我不是JPA的专家，但我认为你需要为每个数据库建立一个单独的持久性单元，你想连接到[2]。
[1] https://cloud.google.com/appengine/docs/java/cloud-sql/#Java_Managing_connections