From 0a86850ba37470837cbd19b33679763851c13b73 Mon Sep 17 00:00:00 2001 From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com> Date: Wed, 5 Aug 2020 09:35:17 +0100 Subject: [PATCH] Stop the parent process flushing the logs on exit (#8012) This solves the problem that the first few lines are logged twice on matrix.org. Hopefully the comments explain it. --- changelog.d/8011.bugfix | 1 + changelog.d/8011.misc | 1 - changelog.d/8012.bugfix | 1 + synapse/util/daemonize.py | 10 ++++++++-- 4 files changed, 10 insertions(+), 3 deletions(-) create mode 100644 changelog.d/8011.bugfix delete mode 100644 changelog.d/8011.misc create mode 100644 changelog.d/8012.bugfix diff --git a/changelog.d/8011.bugfix b/changelog.d/8011.bugfix new file mode 100644 index 0000000000..c673040de9 --- /dev/null +++ b/changelog.d/8011.bugfix @@ -0,0 +1 @@ +Fix a long-standing bug which caused two copies of some log lines to be written when synctl was used along with a MemoryHandler logger. diff --git a/changelog.d/8011.misc b/changelog.d/8011.misc deleted file mode 100644 index dfeb4bdaf1..0000000000 --- a/changelog.d/8011.misc +++ /dev/null @@ -1 +0,0 @@ -Replace daemonize library with a local implementation. diff --git a/changelog.d/8012.bugfix b/changelog.d/8012.bugfix new file mode 100644 index 0000000000..c673040de9 --- /dev/null +++ b/changelog.d/8012.bugfix @@ -0,0 +1 @@ +Fix a long-standing bug which caused two copies of some log lines to be written when synctl was used along with a MemoryHandler logger. diff --git a/synapse/util/daemonize.py b/synapse/util/daemonize.py index a7913fa1af..23393cf49b 100644 --- a/synapse/util/daemonize.py +++ b/synapse/util/daemonize.py @@ -60,8 +60,14 @@ def daemonize_process(pid_file: str, logger: logging.Logger, chdir: str = "/") - process_id = os.fork() if process_id != 0: - # parent process - sys.exit(0) + # parent process: exit. + + # we use os._exit to avoid running the atexit handlers. In particular, that + # means we don't flush the logs. This is important because if we are using + # a MemoryHandler, we could have logs buffered which are now buffered in both + # the main and the child process, so if we let the main process flush the logs, + # we'll get two copies. + os._exit(0) # This is the child process. Continue.