多次调用Web服务时出现问题

Question

我有一个java客户端，它多次调用apache axis web服务（部署在远程机器上的Oracle Application Server上）。

客户端在多个线程之间分发Web服务调用，每个事情都顺利但在平均300个Web服务调用之后（在所有线程中）ab从客户端抛出异常：

java.net.SocketException: Unable to establish connection
at org.apache.axis.AxisFault.makeFault(AxisFault.java:101)
at org.apache.axis.transport.http.HTTPSender.invoke(HTTPSender.java:154)
at org.apache.axis.strategies.InvocationStrategy.visit(InvocationStrategy.java:32)
at org.apache.axis.SimpleChain.doVisiting(SimpleChain.java:11
at org.apache.axis.SimpleChain.invoke(SimpleChain.java:83)
at org.apache.axis.client.AxisClient.invoke(AxisClient.java:165)
at org.apache.axis.client.Call.invokeEngine(Call.java:2784)
at org.apache.axis.client.Call.invoke(Call.java:2767)
at org.apache.axis.client.Call.invoke(Call.java:2443)
at org.apache.axis.client.Call.invoke(Call.java:2366)
at org.apache.axis.client.Call.invoke(Call.java:1812)
at standardwebservice.StandardWebserviceSoapBindingStub.getStandardWebserviceData(StandardWebserviceSoapBindingStub.java:225)
at standardwebservice.StandardWebserviceProxy.getStandardWebserviceData(StandardWebserviceProxy.java:50)
at main.VericalThread.run(VericalThread.java:65)
Caused by: java.net.SocketException: Unable to establish connection
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.axis.components.net.DefaultSocketFactory.create(DefaultSocketFactory.java:153)
at org.apache.axis.components.net.DefaultSocketFactory.create(DefaultSocketFactory.java:120)
at org.apache.axis.transport.http.HTTPSender.getSocket(HTTPSender.java:191)
at org.apache.axis.transport.http.HTTPSender.writeToSocket(HTTPSender.java:404)
at org.apache.axis.transport.http.HTTPSender.invoke(HTTPSender.java:13
... 12 more
Thread No. 1 Start for calling 1210ZD106MAT2AAxisFault
faultCode: {http://schemas.xmlsoap.org/soap/envelope/}Server.userException
faultSubcode:
faultString: java.net.SocketException: Unable to establish connection
faultActor:
faultNode:
faultDetail:
{http://xml.apache.org/axis/}stackTrace:java.net.SocketException: Unable to establish connection
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.axis.components.net.DefaultSocketFactory.create(DefaultSocketFactory.java:153)
at org.apache.axis.components.net.DefaultSocketFactory.create(DefaultSocketFactory.java:120)
at org.apache.axis.transport.http.HTTPSender.getSocket(HTTPSender.java:191)
at org.apache.axis.transport.http.HTTPSender.writeToSocket(HTTPSender.java:404)
at org.apache.axis.transport.http.HTTPSender.invoke(HTTPSender.java:13
at org.apache.axis.strategies.InvocationStrategy.visit(InvocationStrategy.java:32)
at org.apache.axis.SimpleChain.doVisiting(SimpleChain.java:11
at org.apache.axis.SimpleChain.invoke(SimpleChain.java:83)
at org.apache.axis.client.AxisClient.invoke(AxisClient.java:165)
at org.apache.axis.client.Call.invokeEngine(Call.java:2784)
at org.apache.axis.client.Call.invoke(Call.java:2767)
at org.apache.axis.client.Call.invoke(Call.java:2443)
at org.apache.axis.client.Call.invoke(Call.java:2366)
at org.apache.axis.client.Call.invoke(Call.java:1812)
at standardwebservice.StandardWebserviceSoapBindingStub.getStandardWebserviceData(StandardWebserviceSoapBindingStub.java:225)
at standardwebservice.StandardWebserviceProxy.getStandardWebserviceData(StandardWebserviceProxy.java:50)
at main.VericalThread.run(VericalThread.java:65)

顺便说一句，当我在本地计算机（在同一物理网络中）上的oracle应用程序服务器上部署相同的Web服务时，每件事情都顺利，并且不会出现此异常。

顺便说一下，我还尝试了一个JAX-RPC Web服务，并抛出了同样的异常。

所以请有人帮我。