Concurrency with Threads and asyncio

Your learning sequence

1. 1 When Concurrency Helps, and Which Tool to Use Read
2. 2 Not solved yet.○ Download Pages with a Thread Pool Practice · Easy
3. 3 Futures: Getting Results and Errors Back from a Thread Pool Read
4. 4 Not solved yet.○ Collect Results and Errors from a Thread Pool Practice · Easy
5. 5 Threads, Processes and the GIL Read
6. 6 Race Conditions and Locks Read
7. 7 Not solved yet.○ Fix a Counter That Loses Updates Practice · Easy
8. 8 Check and Update Under One Lock Read
9. 9 Not solved yet.○ Build a Counter That Never Goes Over Its Limit Practice · Medium
10. 10 Make Threads Wait Without Polling Read
11. 11 Not solved yet.○ Build a Blocking Queue with a Condition Practice · Medium
12. 12 Catch Thread Errors and Stop Threads Cleanly Read
13. 13 Not solved yet.○ Bring Thread Errors Back to the Caller Practice · Medium
14. 14 Run a Big Batch on a Thread Pool Read
15. 15 Not solved yet.○ Write a Pool Map That Reports Every Failure Practice · Medium
16. 16 asyncio from Zero: Coroutines, await and the Event Loop Read
17. 17 Not solved yet.○ Download Pages at the Same Time with asyncio Practice · Easy
18. 18 Call Async Code from Synchronous Code Read
19. 19 Not solved yet.○ Write a Sync Wrapper for Async Code Practice · Easy
20. 20 Write Type Hints for Async Code Read
21. 21 Not solved yet.○ Accept Any Fetcher You Can Await Practice · Medium
22. 22 Not solved yet.○ Resolve Values, Awaitables and Factories in Order Practice · Medium
23. 23 Stream Paged Results with Async Generators Read
24. 24 Not solved yet.○ Build a Paginator You Can Close Early Practice · Medium
25. 25 Keep Track of Background Tasks Read
26. 26 Not solved yet.○ Build an Owner for Background Tasks Practice · Medium
27. 27 Run Related Tasks Together with TaskGroup Read
28. 28 Not solved yet.○ Fetch Many Pages with a TaskGroup Practice · Medium
29. 29 Cancel a Task and Clean Up After It Read
30. 30 Not solved yet.○ Run Async Cleanup Without Hiding the Real Error Practice · Hard
31. 31 Keep yield Outside Timeouts and TaskGroups Read
32. 32 Not solved yet.○ Batch an Async Stream and Close Its Source Practice · Hard
33. 33 Release Async Resources with contextlib Read
34. 34 Not solved yet.○ Release a Connection However the Stream Ends Practice · Hard
35. 35 Set Timeouts and Share One Deadline Read
36. 36 Not solved yet.○ Retry Within One Shared Deadline Practice · Medium
37. 37 Write Async Context Managers That Clean Up Read
38. 38 Feed Workers Through a Bounded Queue Read
39. 39 Not solved yet.○ Process a Stream with a Bounded Queue Practice · Medium
40. 40 Run Blocking Calls from Async Code Read
41. 41 Not solved yet.○ Build a Typed Async Wrapper for Blocking Calls Practice · Medium
42. 42 Shut Down an asyncio Service Gracefully Read
43. 43 Not solved yet.○ Build a Service That Shuts Down in Stages Practice · Hard
44. 44 Debug a Slow or Stuck Async Service Read
45. 45 Carry a Request ID Across Tasks with contextvars Read
46. 46 Not solved yet.○ Build a Request ID That Follows Tasks and Threads Practice · Medium
47. 47 Start Tasks Right Away with Eager Tasks Read
48. 48 Limit Concurrency, Request Rate and Queued Work Read
49. 49 Not solved yet.○ Map Over a Stream with at Most N Calls at Once Practice · Hard
50. 50 Choose Between asyncio, AnyIO and Trio Read
51. 51 Fix Disagreements Between mypy and Pyright Read
52. 52 Choose the Right Concurrency Tool for Each Job Read
53. 53 Write Concurrency Tests with Events, Not Sleeps Read
54. 54 Make Async Tests Repeatable with Handshakes and Fake Clocks Read
55. 55 Not solved yet.○ Find Leaked Tasks and Start Threads Together Practice · Medium
56. 56 Not solved yet.○ Capstone: Build an Async Worker Pool with Retries and Clean Shutdown Practice · Hard

from threading import Lock, RLock

lock = Lock()
first = lock.acquire()
second = lock.acquire(blocking=False)
print(first, second)
lock.release()

rlock = RLock()
first = rlock.acquire()
second = rlock.acquire(blocking=False)
print(first, second)
rlock.release()
rlock.release()