Couchbase + xmemcached

I am using couchbase and xmemcached client in multithreaded java SE application. I am constantly observing that couchbase is unable to save last few keys whereas traditional memcached is setting all keys excellently. I am using exaclty same xmemcachedclient configuration in both cases.

Spring Configuration

<bean name="memcachedClient" class="net.rubyeye.xmemcached.utils.XMemcachedClientFactoryBean" destroy-method="shutdown">
<property name="configuration">
  <bean class="">
     <property name="handleReadWriteConcurrently" value="true" />
<property name="servers">
<!-- server's weights -->
<property name="weights">
<!-- nio connection pool size -->
<!-- <property name="connectionPoolSize" value="4"></property> -->
<!-- Use binary protocol,default is TextCommandFactory -->
<property name="commandFactory">
  <bean class="net.rubyeye.xmemcached.command.BinaryCommandFactory" />
<!-- Distributed strategy -->
<property name="sessionLocator">
  <bean class="net.rubyeye.xmemcached.impl.KetamaMemcachedSessionLocator" />
<!-- Serializing transcoder -->
<property name="transcoder">
  <bean class="net.rubyeye.xmemcached.transcoders.SerializingTranscoder" />
<!-- ByteBuffer allocator -->
<property name="bufferAllocator">
  <bean class="net.rubyeye.xmemcached.buffer.SimpleBufferAllocator" />

below is my test code that checks for missing keys

public void test100000HitMiss() 
    ArrayList<Integer> hits = new ArrayList<Integer>();
    ArrayList<Integer> misses = new ArrayList<Integer>();

    for(Integer i=0; i < 100000; i++)
            Object val = memcachedClient.get("2/C/TALAL" + i.toString());

            if(null == val)
        catch (Exception ex) 
    }"Hits: " + hits.size() + " - Misses: " + misses.size());


Every time I run this test, I get 3 or 4 keys in misses array

Know someone who can answer?

@deniswsrosa can you assist please ?