org.postgresql.util。PSQLException:连接尝试失败。

I am connecting to postgres data base using java web services (apache axis) with JDBC connections to get the data.But suddenly in most of times i am getting an exception of org.postgresql.util.PSQLException: The connection attempt failed. and some times it is working fine. Here I am using many prepared statements. My sample code is

我正在使用java web服务(apache axis)和JDBC连接连接到postgres数据库，以获取数据。但是，在大多数情况下，我突然得到了一个例外。PSQLException:连接尝试失败。有时它运行得很好。这里我使用了许多准备好的语句。我的示例代码

Connection connection=null;
try
{
    Class.forName(driver);
    connection = DriverManager.getConnection(url, username, password);
    ps1=connection.prepareStatement("select * from emp");
    rs1=ps1.executeQuery();
    while(rs1.next())
    {            
        ps2=connection.prepareStatement("select * from dept where dept_no="+rs1.getInt("dept_no"));
        rs2=ps2.executeQuery();
        while(rs2.next())
        {
            ................
            ................
        }
    }
}
catch(Exception e)
{
    System.out.println("Exception occurred is"+e.getMessage());            
}
finally
{
    try{if(rs1!=null)rs1.close();}catch(Exception e){ System.out.println("*1closing error--->"+e);}
    try{if(ps1!=null)ps1.close();}catch(Exception e){ System.out.println("**1closing error--->"+e);}
    try{if(rs2!=null)rs2.close();}catch(Exception e){ System.out.println("*2closing error--->"+e);}
    try{if(ps2!=null)ps2.close();}catch(Exception e){ System.out.println("**2closing error--->"+e);}
    try{if(connection!=null)connection.close();}catch(Exception e){ System.out.println("***closing error--->"+e);}
}

stack trace about this exception is

关于这个异常的堆栈跟踪。

org.postgresql.util.PSQLException: The connection attempt failed.
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:137)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:66)
    at org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:124)
    at org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:30)
    at org.postgresql.jdbc3.Jdbc3Connection.<init>(Jdbc3Connection.java:24)
    at org.postgresql.Driver.makeConnection(Driver.java:386)
    at org.postgresql.Driver.connect(Driver.java:260)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.codon.service.WareHouseServer.get_picks(WareHouseServer.java:7415)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.apache.axis.providers.java.RPCProvider.invokeMethod(RPCProvider.java:397)
    at org.apache.axis.providers.java.RPCProvider.processMessage(RPCProvider.java:186)
    at org.apache.axis.providers.java.JavaProvider.invoke(JavaProvider.java:323)
    at org.apache.axis.strategies.InvocationStrategy.visit(InvocationStrategy.java:32)
    at org.apache.axis.SimpleChain.doVisiting(SimpleChain.java:118)
    at org.apache.axis.SimpleChain.invoke(SimpleChain.java:83)
    at org.apache.axis.handlers.soap.SOAPService.invoke(SOAPService.java:454)
    at org.apache.axis.server.AxisServer.invoke(AxisServer.java:281)
    at org.apache.axis.transport.http.AxisServlet.doPost(AxisServlet.java:699)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at org.apache.axis.transport.http.AxisServletBase.service(AxisServletBase.java:327)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.net.SocketException: Connection reset
    at java.net.SocketInputStream.read(Unknown Source)
    at org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:135)
    at org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:104)
    at org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:73)
    at org.postgresql.core.PGStream.ReceiveChar(PGStream.java:259)
    at org.postgresql.core.v3.ConnectionFactoryImpl.doAuthentication(ConnectionFactoryImpl.java:254)
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:95)
    ... 37 more

I checked the postgres logs and i found the following statements in different cases

我检查了postgres日志，并在不同的情况下找到了下面的语句。

1.WARNING: worker took too long to start; cancelled.

1。警告:工作时间过长;取消了。

2.could not reattach to shared memory (key=...., addr=.....): 487.

2。不能重新连接到共享内存(键=addr = .....):487。

3.could not receive data from client: No connection could be made because the target machine actively refused it.

3所示。无法从客户端接收数据:无法连接，因为目标机主动拒绝。

4.unexpected EOF on client connection.

4所示。客户端连接意外的EOF。

please help me.Thanks In advance

请帮助我。谢谢提前

1 个解决方案

#1

The real problem is:

真正的问题是:

Caused by: java.net.SocketException: Connection reset
    at java.net.SocketInputStream.read

The connection was closed when Java tried to read from it. This can be caused by:

当Java试图从中读取时，连接被关闭。这可能是由于:

The PostgreSQL server being restarted
正在重新启动的PostgreSQL服务器。
The PostgreSQL backend you were connected to being terminated
您连接到的PostgreSQL后端将被终止。
The PostgreSQL backend you were connected to crashing
PostgreSQL后端连接到崩溃。
Dodgy network connection
不可靠的网络连接
Badly behaved stateful firewalls
表现不好的有状态的防火墙
Idle connections timing out of the NAT connection tables of NAT firewall/routers
NAT防火墙/路由器的NAT连接表的空闲连接时间。

... and probably more. Check the PostgreSQL server logs to see if there's anything informative there; also consider doing some network tracing with a tool like Wireshark.

…而且可能更多。检查PostgreSQL server日志，看看是否有什么有用的信息;还可以考虑使用像Wireshark这样的工具进行一些网络跟踪。

#1