Reason for Xmemcached is stopped in a high traffic website

[Kiran]

In a high traffic multithreaded environment, a java  Thread in its while (true ) condition continoulsy does operatios on Memcached .( set , get , cas , delete ) 

Very frequently we see this exception 

net.rubyeye.xmemcached.exception.MemcachedException: Xmemcached is stopped

at net.rubyeye.xmemcached.XMemcachedClient.sendCommand(XMemcachedClient.java:247)

at net.rubyeye.xmemcached.XMemcachedClient.fetch0(XMemcachedClient.java:573)

at net.rubyeye.xmemcached.XMemcachedClient.get0(XMemcachedClient.java:971)

at net.rubyeye.xmemcached.XMemcachedClient.get(XMemcachedClient.java:929)

at net.rubyeye.xmemcached.XMemcachedClient.get(XMemcachedClient.java:940)

at net.rubyeye.xmemcached.XMemcachedClient.get(XMemcachedClient.java:962)

COuld anybody please tell me what might be the cause for this exception .

It comes at a time , and couldn't try to reproduce it manually 

Thanks 

[Kiran]

By the way we are using xmemcached 1.3.8 , on Ubuntu , Memcache 1.4.15 with repcached 2.3.1 .