What is Thread Local Storage?
Thread Local Storage is a means where variables declared as thread local are made specific to thread instances.
Use cases of Thread Local Storage include -
- The famous error variable errno in C, declared global without thread synchronization is prone to overwrites in multithreaded environments
- Need of Thread specific counters
- To maintain contexts required by a complex application which could be on a per user or per session or per transaction basis
How Thread Local Storage is supported in Python:
The threading module in python provides the 'local' class for TLS - Thread Local Storage purposes.
The variable that needs to be made thread local is declared as an attributed of a local() instance and this attribute is accessed later.
Example of Thread Local Storage in Python:
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# Thread Local Storage: Example Python Program
import threading
userName = threading.local()
def SessionThread(userName_in): userName.val = userName_in print(userName.val)
Session1 = threading.Thread(target=SessionThread("User1")) Session2 = threading.Thread(target=SessionThread("User2"))
# start the session threads Session1.start() Session2.start()
# wait till the session threads are complete Session1.join() Session2.join() |