# Running Multiple Instances of PRAW

PRAW, as of version 4, performs rate limiting dynamically based on the HTTP response headers from Reddit. As a result you can safely run a handful of PRAW instances without any additional configuration.

Note

Running more than a dozen or so instances of PRAW concurrently from may occasionally result in exceeding Reddit’s rate limits as each instance can only guess how many other instances are running.

If you are authorized on other users behalf, each authorization should have its own rate limit, even when running from a single IP address.

## Multiple Programs

The recommended way to run multiple instances of PRAW is to simply write separate independent python programs. With this approach one program can monitor a comment stream and reply as needed, and another program can monitor a submission stream, for example.

If these programs need to share data consider using a third party system such as a database, or queuing system.

## Multiple Threads

Warning

PRAW is not thread safe.

In a nutshell, instances of `Reddit` are not thread safe for a number of reasons in its own code and each instance depends on an instance of `requests.Session`, which is not thread safe [ref].

In theory having a unique `Reddit` instance for each thread should work. However, until someone perpetually volunteers to be PRAW’s thread safety instructor, little to no support will go toward any PRAW issues that could be affected by the use of multiple threads. Consider using multiple processes instead.

Please see this discussion for more information.