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Measure a block

Use the Timer as a context manager to measure a single block of code. The Timer creates one Measurement per block; wall_time and cpu_time are set on block exit.

Syntax

from timerun import Timer

with Timer() as m:
    pass  # code block to be measured

m.wall_time.timedelta   # datetime.timedelta
m.cpu_time.timedelta    # datetime.timedelta

from timerun import Timer

async with Timer() as m:
    await do_something()

m.wall_time.timedelta   # datetime.timedelta
m.cpu_time.timedelta    # datetime.timedelta

Wall vs CPU time and sampling order are explained in Timer overview: How timing works.

Behavior summary

Scenario Behavior
Single block One measurement; wall_time and cpu_time set on exit.
Sequential blocks (same Timer) One measurement per block; each block receives its own measurement with a fresh copy of the initial metadata.
Nested blocks (same Timer) Outer and inner each receive one measurement; timings are independent (outer wall time includes the inner block’s wall time).
Multiple threads (same Timer) One measurement per thread per enter/exit; each thread has its own independent stack, so threads do not interfere with each other.
Concurrent asyncio tasks (same Timer) One measurement per task per enter/exit; each asyncio task has its own independent stack (like threads in sync mode), so concurrent tasks do not interfere with each other.
Invalid use: async with outside a task RuntimeError with message "no current asyncio task" (for example if async with Timer() is used from synchronous code without a current asyncio task).
Exception in block The measurement is still recorded (wall/cpu set on exit); the exception propagates to the caller.
Invalid use: __exit__ without __enter__ RuntimeError with message "__exit__ called without a matching __enter__".

The same Timer instance can be reused for multiple blocks (sequential or nested). Each block receives its own Measurement; metadata mutations in one block do not appear in the next (see Metadata).