Oozie Tasks Cannot Be Submitted on a Client Outside the MRS Cluster or Can Be Submitted Only Two Hours Later

Symptom

A user on a client outside the MRS cluster failed to submit Oozie tasks or successfully submitted them only two hours later.

Cause Analysis

Some background logs about the Java secure random number are found. In the JDK, the SecureRandom algorithm depends on the random data provided by the OS. In the Linux OS, /dev/random and /dev/urandom store data related to the secure random number. When the entropy pool is empty, read operations from /dev/random are blocked until the entropy pool collects enough environment noise data. As a result, task submission becomes slow or fails.

Procedure

1. Run the following command on the node where the client outside the cluster is located to install rng-tools:

   yum install rng-tools

2. Run the following command to start rng-tools:

   systemctl start rngd

   To enable rng-tools to automatically run after its node is restarted, run the following command:

   systemctl enable rngd

3. Run the Oozie task again.