Skip to main content

Bcrypt and slow tests

We use Bcrypt hash to encrypt user's password. One of the strength of bcrypt is that its inherently slow to compute the hash and that makes the brute force breaking of password almost impossible.  But I recently ran into an interesting issue where almost overnight the build times on jenkins blow up from 12 mins to 22 mins and the build engineer complained about bulk user testcase as the culprit.

I ran it locally and found that the class had close to 15 tests and each test method was taking 20 sec and all I see is in setup we were creating 5 users and deleting 5 users in teardown.  So as usual best way to debug a performance problem is to look at the thread dump. I did a ps -ef on the running build and did a kill -QUIT to print the thread dump and immediately I saw time spent in Bcrypt computation. I took 3-4 more thread dump and all of them were stuck on bcrypt.  So I did two things:

1) I saw many methods in the test class that were testing pure validations and didnt needed the creation/deletion of users. So I moved them to a new Unit test class.
2) I added a JVM property to skip Bcrypt computation during user creation and passed that as a jvm argument to ant test target. This is to prevent not the skip in the prod environment.

And voila the build times were back to 13 mins.

Comments

Popular posts from this blog

RabbitMQ java clients for beginners

Here is a sample of a consumer and producer example for RabbitMQ. The steps are
Download ErlangDownload Rabbit MQ ServerDownload Rabbit MQ Java client jarsCompile and run the below two class and you are done.
This sample create a Durable Exchange, Queue and a Message. You will have to start the consumer first before you start the for the first time.

For more information on AMQP, Exchanges, Queues, read this excellent tutorial
http://blogs.digitar.com/jjww/2009/01/rabbits-and-warrens/

+++++++++++++++++RabbitMQProducer.java+++++++++++++++++++++++++++
import com.rabbitmq.client.Connection; import com.rabbitmq.client.Channel; import com.rabbitmq.client.*; public class RabbitMQProducer { public static void main(String []args) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setUsername("guest"); factory.setPassword("guest"); factory.setVirtualHost("/"); factory.setHost("127.0.0.1"); factory.setPort(5672); Conne…

What a rocky start to labor day weekend

Woke up by earthquake at 7:00 AM in morning and then couldn't get to sleep. I took a bath, made my tea and started checking emails and saw that after last night deployment three storage node out of 100s of nodes were running into Full GC. What was special about the 3 nodes was that each one was in a different Data centre but it was named same app02.  This got me curious I asked the node to be taken out of rotation and take a heap dump.  Yesterday night a new release has happened and I had upgraded spymemcached library version as new relic now natively supports instrumentation on it so it was a suspect. And the hunch was a bullseye, the heap dump clearly showed it taking 1.3G and full GCs were taking 6 sec but not claiming anything.



I have a quartz job in each jvm that takes a thread dump every 5 minutes and saves last 300 of them, checking few of them quickly showed a common thread among all 3 data centres. It seems there was a long running job that was trying to replicate pending…

Email slavery

It seems I have become an EmailSlave. The first half of the day is spent in just answering to emails. There are so many emails where I am copied but I need not be. There are many emails  where its a 1-2 page email and somewhere down someone says @KP please answer this.  So it seems daily my work schedule is:
Signin to newrelic and check anomalies for 15 min. Check emails related production exception report and yes there are a ton of these report daily. Need a better tool here as this model is not scalable. I need to reduce the incoming data at me to only see relevant data like what newrelic does. May be I need to create a webapp out of these emails.Check emails for next few minutes before team callsDo team callsThen again back to checking emails until a I have taken a best shot at answering everyone waiting for my reply.Attend team meetings on Tue/Thu
Being an architect and coder at heart I don't feel satisfied at end of the day if there is nothing tangible getting done at the end.…