diff options
| -rw-r--r-- | changelog.d/7663.bugfix | 1 | ||||
| -rw-r--r-- | synapse/config/cache.py | 20 |
2 files changed, 16 insertions, 5 deletions
diff --git a/changelog.d/7663.bugfix b/changelog.d/7663.bugfix new file mode 100644 index 0000000000..b58316b34f --- /dev/null +++ b/changelog.d/7663.bugfix @@ -0,0 +1 @@ +Fix intermittent exception during startup, introduced in Synapse 1.14.0. diff --git a/synapse/config/cache.py b/synapse/config/cache.py index 0672538796..aff5b21ab2 100644 --- a/synapse/config/cache.py +++ b/synapse/config/cache.py @@ -15,6 +15,7 @@ import os import re +import threading from typing import Callable, Dict from ._base import Config, ConfigError @@ -25,6 +26,9 @@ _CACHE_PREFIX = "SYNAPSE_CACHE_FACTOR" # Map from canonicalised cache name to cache. _CACHES = {} +# a lock on the contents of _CACHES +_CACHES_LOCK = threading.Lock() + _DEFAULT_FACTOR_SIZE = 0.5 _DEFAULT_EVENT_CACHE_SIZE = "10K" @@ -66,7 +70,10 @@ def add_resizable_cache(cache_name: str, cache_resize_callback: Callable): # Some caches have '*' in them which we strip out. cache_name = _canonicalise_cache_name(cache_name) - _CACHES[cache_name] = cache_resize_callback + # sometimes caches are initialised from background threads, so we need to make + # sure we don't conflict with another thread running a resize operation + with _CACHES_LOCK: + _CACHES[cache_name] = cache_resize_callback # Ensure all loaded caches are sized appropriately # @@ -87,7 +94,8 @@ class CacheConfig(Config): os.environ.get(_CACHE_PREFIX, _DEFAULT_FACTOR_SIZE) ) properties.resize_all_caches_func = None - _CACHES.clear() + with _CACHES_LOCK: + _CACHES.clear() def generate_config_section(self, **kwargs): return """\ @@ -193,6 +201,8 @@ class CacheConfig(Config): For each cache, run the mapped callback function with either a specific cache factor or the default, global one. """ - for cache_name, callback in _CACHES.items(): - new_factor = self.cache_factors.get(cache_name, self.global_factor) - callback(new_factor) + # block other threads from modifying _CACHES while we iterate it. + with _CACHES_LOCK: + for cache_name, callback in _CACHES.items(): + new_factor = self.cache_factors.get(cache_name, self.global_factor) + callback(new_factor) |