From ccc360317094b12cb0fb95b911a33a7590d2698a Mon Sep 17 00:00:00 2001 From: Henrique Goulart Date: Fri, 13 Sep 2024 16:54:27 -0300 Subject: [PATCH] docs: add note about PYTHONMALLOC for accurate jemalloc memory tracking Added a note in the documentation suggesting that users may set `PYTHONMALLOC=malloc` when using `jemalloc`. This allows jemalloc to track memory usage more accurately by bypassing Python's internal small-object allocator (`pymalloc`), helping to ensure that cache_autotuning functions as expected. This doc change aims to provide more clarity for users configuring jemalloc with Synapse. --- docs/usage/administration/admin_faq.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/docs/usage/administration/admin_faq.md b/docs/usage/administration/admin_faq.md index a1184d0375..0dce3d3e37 100644 --- a/docs/usage/administration/admin_faq.md +++ b/docs/usage/administration/admin_faq.md @@ -255,6 +255,8 @@ line to `/etc/default/matrix-synapse`: LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2 +*Note*: You may need to set `PYTHONMALLOC=malloc` to ensure that `jemalloc` can accurately calculate memory usage. By default, Python uses its internal small-object allocator, which may interfere with jemalloc's ability to track memory consumption correctly. This could prevent the [cache_autotuning](../configuration/config_documentation.md#caches-and-associated-values) feature from functioning as expected, as the Python allocator may not reach the memory threshold set by `max_cache_memory_usage`, thus not triggering the cache eviction process. + This made a significant difference on Python 2.7 - it's unclear how much of an improvement it provides on Python 3.x.