is mule session variable thread safe?

Question

Hi I have a complex flow where my payload is getting modified along with original payload. In order to get the original payload I am storing the initial payload in a mule session variable so that I can use that variable(original payload) down the flow. This process is working but my concern is my mule session variable thread safe?
I tried choosing invocation,outbound scope but I found that variable value become null down the flow after some processing and transformation.

Any input would be greatly appreciated. Thanks

Answer 1

The mule message is processed by one thread at a time, so variables or properties (any scope) in the mule message don't need to be thread-safe. Invocation scope should be enough if you want to use a property in a single flow.

Answer 2

Apparently, the session variables are not thread safe. I used a session variable in a flow that has splitter and aggregator for parallel execution of a piece of code (which modifies the same session variable). Found that it overwrites the data inside the splitter thread!

Answer 3

Session variable is meant for storing values which need to be reference after the flow passes through a transport barrier which could be any connector. Within the same flow session variable is thread safe.