问题
I am using the Datastax Cassandra driver and have a RetryPolicy setup to retry when a host is unavailable. However, I have noticed that it retries as fast as it can. I would like to change it to have an increasing delay between retries rather than hammer the cluster if it is struggling. This is particularly important for OVERLOADED request errors since I do want to retry in these scenarios, but with a substantial delay.
Where is the right place to put a delay and what is the right mechanism? Should I just throw a Thread.sleep(...) in my RetryPolicy?
I don't mind taking up a request on-the-wire slot (towards the maximum number of in-flight requests) but I am not okay with completely blocking other writes if we are not yet at the in-flight request limit.
回答1:
You can implement your own retry policy by adding a delay. The simplest way is to pick the source code of the default retry and modify it yourself to implement an exponential delay for retry or something similar.
For exponential delay, just look at the source code of http://docs.datastax.com/en/drivers/java/3.0/com/datastax/driver/core/policies/ExponentialReconnectionPolicy.html to see how it works
来源：https://stackoverflow.com/questions/35562640/datastax-cassandra-driver-retry-policy-delay