Hi,
seems this is a memory leak at slave as there are too many objects in attached DumpExportTable of slave.
slave log having below lines in last at log .

slave connected to master with parameter -Xms2g -Xmx2g -XX:MaxPermSize=512m.

hudson.util.ProcessTree getKillers
WARNING: Failed to obtain killers
java.io.IOException: Remote call on channel failed
at hudson.remoting.Channel.call(Channel.java:690)
at hudson.util.ProcessTree.getKillers(ProcessTree.java:160)
at hudson.util.ProcessTree$OSProcess.killByKiller(ProcessTree.java:219)
at hudson.util.ProcessTree$UnixProcess.kill(ProcessTree.java:552)
at hudson.util.ProcessTree$UnixProcess.killRecursively(ProcessTree.java:559)
at hudson.util.ProcessTree$UnixProcess.killRecursively(ProcessTree.java:558)
at hudson.util.ProcessTree.killAll(ProcessTree.java:147)
at hudson.Proc$LocalProc.destroy(Proc.java:379)
at hudson.Proc$LocalProc.join(Proc.java:352)
at hudson.Launcher$RemoteLaunchCallable$1.join(Launcher.java:937)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:274)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:255)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:215)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:287)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.OutOfMemoryError: GC overhead limit exceeded