diff options
Diffstat (limited to 'synapse/config/cache.py')
| -rw-r--r-- | synapse/config/cache.py | 82 |
1 files changed, 64 insertions, 18 deletions
diff --git a/synapse/config/cache.py b/synapse/config/cache.py index 94d852f413..d2f55534d7 100644 --- a/synapse/config/cache.py +++ b/synapse/config/cache.py @@ -69,11 +69,11 @@ def _canonicalise_cache_name(cache_name: str) -> str: def add_resizable_cache( cache_name: str, cache_resize_callback: Callable[[float], None] ) -> None: - """Register a cache that's size can dynamically change + """Register a cache whose size can dynamically change Args: cache_name: A reference to the cache - cache_resize_callback: A callback function that will be ran whenever + cache_resize_callback: A callback function that will run whenever the cache needs to be resized """ # Some caches have '*' in them which we strip out. @@ -96,6 +96,13 @@ class CacheConfig(Config): section = "caches" _environ = os.environ + event_cache_size: int + cache_factors: Dict[str, float] + global_factor: float + track_memory_usage: bool + expiry_time_msec: Optional[int] + sync_response_cache_duration: int + @staticmethod def reset() -> None: """Resets the caches to their defaults. Used for tests.""" @@ -115,6 +122,12 @@ class CacheConfig(Config): # A cache 'factor' is a multiplier that can be applied to each of # Synapse's caches in order to increase or decrease the maximum # number of entries that can be stored. + # + # The configuration for cache factors (caches.global_factor and + # caches.per_cache_factors) can be reloaded while the application is running, + # by sending a SIGHUP signal to the Synapse process. Changes to other parts of + # the caching config will NOT be applied after a SIGHUP is received; a restart + # is necessary. # The number of events to cache in memory. Not affected by # caches.global_factor. @@ -163,6 +176,24 @@ class CacheConfig(Config): # #cache_entry_ttl: 30m + # This flag enables cache autotuning, and is further specified by the sub-options `max_cache_memory_usage`, + # `target_cache_memory_usage`, `min_cache_ttl`. These flags work in conjunction with each other to maintain + # a balance between cache memory usage and cache entry availability. You must be using jemalloc to utilize + # this option, and all three of the options must be specified for this feature to work. + #cache_autotuning: + # This flag sets a ceiling on much memory the cache can use before caches begin to be continuously evicted. + # They will continue to be evicted until the memory usage drops below the `target_memory_usage`, set in + # the flag below, or until the `min_cache_ttl` is hit. + #max_cache_memory_usage: 1024M + + # This flag sets a rough target for the desired memory usage of the caches. + #target_cache_memory_usage: 758M + + # 'min_cache_ttl` sets a limit under which newer cache entries are not evicted and is only applied when + # caches are actively being evicted/`max_cache_memory_usage` has been exceeded. This is to protect hot caches + # from being emptied while Synapse is evicting due to memory. + #min_cache_ttl: 5m + # Controls how long the results of a /sync request are cached for after # a successful response is returned. A higher duration can help clients with # intermittent connections, at the cost of higher memory usage. @@ -174,21 +205,21 @@ class CacheConfig(Config): """ def read_config(self, config: JsonDict, **kwargs: Any) -> None: + """Populate this config object with values from `config`. + + This method does NOT resize existing or future caches: use `resize_all_caches`. + We use two separate methods so that we can reject bad config before applying it. + """ self.event_cache_size = self.parse_size( config.get("event_cache_size", _DEFAULT_EVENT_CACHE_SIZE) ) - self.cache_factors: Dict[str, float] = {} + self.cache_factors = {} cache_config = config.get("caches") or {} - self.global_factor = cache_config.get( - "global_factor", properties.default_factor_size - ) + self.global_factor = cache_config.get("global_factor", _DEFAULT_FACTOR_SIZE) if not isinstance(self.global_factor, (int, float)): raise ConfigError("caches.global_factor must be a number.") - # Set the global one so that it's reflected in new caches - properties.default_factor_size = self.global_factor - # Load cache factors from the config individual_factors = cache_config.get("per_cache_factors") or {} if not isinstance(individual_factors, dict): @@ -230,7 +261,7 @@ class CacheConfig(Config): cache_entry_ttl = cache_config.get("cache_entry_ttl", "30m") if expire_caches: - self.expiry_time_msec: Optional[int] = self.parse_duration(cache_entry_ttl) + self.expiry_time_msec = self.parse_duration(cache_entry_ttl) else: self.expiry_time_msec = None @@ -250,23 +281,38 @@ class CacheConfig(Config): ) self.expiry_time_msec = self.parse_duration(expiry_time) + self.cache_autotuning = cache_config.get("cache_autotuning") + if self.cache_autotuning: + max_memory_usage = self.cache_autotuning.get("max_cache_memory_usage") + self.cache_autotuning["max_cache_memory_usage"] = self.parse_size( + max_memory_usage + ) + + target_mem_size = self.cache_autotuning.get("target_cache_memory_usage") + self.cache_autotuning["target_cache_memory_usage"] = self.parse_size( + target_mem_size + ) + + min_cache_ttl = self.cache_autotuning.get("min_cache_ttl") + self.cache_autotuning["min_cache_ttl"] = self.parse_duration(min_cache_ttl) + self.sync_response_cache_duration = self.parse_duration( cache_config.get("sync_response_cache_duration", 0) ) - # Resize all caches (if necessary) with the new factors we've loaded - self.resize_all_caches() - - # Store this function so that it can be called from other classes without - # needing an instance of Config - properties.resize_all_caches_func = self.resize_all_caches - def resize_all_caches(self) -> None: - """Ensure all cache sizes are up to date + """Ensure all cache sizes are up-to-date. For each cache, run the mapped callback function with either a specific cache factor or the default, global one. """ + # Set the global factor size, so that new caches are appropriately sized. + properties.default_factor_size = self.global_factor + + # Store this function so that it can be called from other classes without + # needing an instance of CacheConfig + properties.resize_all_caches_func = self.resize_all_caches + # block other threads from modifying _CACHES while we iterate it. with _CACHES_LOCK: for cache_name, callback in _CACHES.items(): |