jedis – Robin on Linux

Performance bottleneck in Jedis

I have had write a test program which using Jedis to read/write Redis Cluster. It create 32 threads and every thread init a instance of JedisCLuster(). But it will cost more than half minute to create total 32 JedisCluster Instances.
By tracking the problem, I found out that the bottleneck is in setNodeIfNotExist():

JedisCluster()
    --> BinaryJedisCluster()
        --> JedisSlotBasedConnectionHandler()
            --> JedisClusterInfoCache()
                --> discoverClusterNodesAndSlots()
                    --> setNodeIfNotExist()

In the method setNodeIfNotExist() of class JedisClusterInfoCache, “new JedisPool()” will cost a lot of time because it will use apache commons pool and apache-commons-pool will register MBean Server with JMX. The register operation of JMX is the bottelneck.

The first solution for this problem is to disable JMX when calling JedisCluster():

GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
poolConfig.setJmxEnabled(false);
client = JedisCluster(nodesSet, poolConfig);

The second solution is “create one JedisCluster() instance for all threads”. After I commited patch for Jedis to set JMX disable as default, Marcos Nils remind me that JedisCluster() is thread-safe, for it has using commons-pool to manage the connection resource.

From scala Array[String] / Seq[String] to java varargs

While testing performance of redis these days, I need to use mset() interface of jedis (a java version redis client). But the prototype of mset() in jedis is:

@Override
  public String mset(final String... keysvalues) {

Firstly I write my scala code like:

var array = Array[String]()
array = array:+key1:+value1
array = array:+key2:+value2
jedis.mset(array)

But it report compiling errors:

[error] xxx: overloaded method value mset with alternatives:
[error]   (x$1: String*)String 
[error]   (x$1: Array[Byte]*)String
[error]  cannot be applied to (Array[String])
[error]                                 jedis.mset(array)
[error]                                       ^
[error] one error found
[error] (compile:compileIncremental) Compilation failed
[error] Total time: 4 s, completed Jan 8, 2016 11:32:47 AM

After searching many documents about scala/java on google, I finally find the answer: http://docs.scala-lang.org/style/types.html. So, let’s write code this way:

jedis.mset(array:_*)

Then Array[String] of scala changes to varargs in java now. It also viable for Seq[String].