java SDK for memcache 测试并发读取时，10个以上并发就会出现鉴权问题

使用java SDK测试memcache的并发读取时，每次读取都建立一个连接，读取完后关闭。并发测试时，均会报错，如下，请问是什么原因？

2017-05-31 15:34:25.097 WARN net.spy.memcached.protocol.binary.BinaryMemcachedNodeImpl: Operation canceled because authentication or reconnection and authentication has taken more than one second to complete.
java.lang.RuntimeException: Exception waiting for value

at net.spy.memcached.MemcachedClient.get(MemcachedClient.java:1007)
at net.spy.memcached.MemcachedClient.get(MemcachedClient.java:1024)
at cci.com.hk.company500.memcache.GetCompareCompanys4China.doPost(GetCompareCompanys4China.java:60)
at cci.com.hk.company500.memcache.GetCompareCompanys4China.doGet(GetCompareCompanys4China.java:26)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:475)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:498)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:796)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1366)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)

Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: Cancelled

at net.spy.memcached.internal.OperationFuture.get(OperationFuture.java:169)
at net.spy.memcached.internal.GetFuture.get(GetFuture.java:62)
at net.spy.memcached.MemcachedClient.get(MemcachedClient.java:1003)
... 27 more

Caused by: java.lang.RuntimeException: Cancelled

... 30 more