From 8027538bb003c7f174c7f3a92be3671d6fc39c51 Mon Sep 17 00:00:00 2001 From: Bradlee Speice Date: Tue, 30 Jun 2020 17:53:02 -0400 Subject: [PATCH] Proofreading --- _posts/2020-06-29-release-the-gil-pt.-2.md | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/_posts/2020-06-29-release-the-gil-pt.-2.md b/_posts/2020-06-29-release-the-gil-pt.-2.md index 662cdc2..6a8d8e7 100644 --- a/_posts/2020-06-29-release-the-gil-pt.-2.md +++ b/_posts/2020-06-29-release-the-gil-pt.-2.md @@ -92,8 +92,8 @@ PYBIND11_MODULE(speiceio_pybind11, m) { } ``` -After the code is installed into a `virtualenv` or similar setup, we can use the functions to -demonstrate GIL unlocking: +After building the C++ module, those functions can be used to demonstrate the effect of unlocking +the GIL. ```python # The billionth Fibonacci number overflows `std::uint64_t`, but that's OK; @@ -103,7 +103,7 @@ N = 1_000_000_000; from speiceio_pybind11 import fibonacci_gil, fibonacci_nogil ``` -Even when using two threads, the code is effectively serial: +Even though two threads are used, the GIL prevents those threads from running in parallel: ```python %%time @@ -123,9 +123,11 @@ t1.join(); t2.join() > Wall time: 705 ms > -The elapsed ("wall") time is effectively the same as the time spent executing on the CPU ("user"). +Because the elapsed ("wall") time is effectively the same as the time spent executing on the CPU +("user"), there was no benefit to using multiple threads. -However, if one thread unlocks the GIL first, then the threads will execute in parallel: +However, if one thread unlocks the GIL first, the Python interpreter is allowed to execute the +second thread in parallel: ```python %%time @@ -141,9 +143,10 @@ t1.join(); t2.join() > Wall time: 372 ms > -The CPU time ("user") hasn't changed, but the elapsed time ("wall") is effectively cut in half. +The CPU time ("user") hasn't changed much, but the elapsed time ("wall") is effectively cut in half. -TODO: Note about double-unlocking: +Caution is advised though; attempting to unlock the GIL when it isn't locked will terminate the +current process: ```c++ void recurse_unlock() {