Optimize map capacity allocation during shard initialization.
Author: xiaobai12011Created Feb 4, 2026Updated Feb 5, 2026
If StatsEnabled is configured as false, could we consider not allocating a ShardSize size for hashmapStats during the Shard initialization function (initNewShard)? This is because the data is not used in subsequent processes, resulting in the allocation of invalid memory space. This issue is more pronounced when caching a large number of entries.
func initNewShard(config Config, callback onRemoveCallback, clock clock) *cacheShard {
bytesQueueInitialCapacity := config.initialShardSize() * config.MaxEntrySize
maximumShardSizeInBytes := config.maximumShardSizeInBytes()
if maximumShardSizeInBytes > 0 && bytesQueueInitialCapacity > maximumShardSizeInBytes {
bytesQueueInitialCapacity = maximumShardSizeInBytes
}
return &cacheShard{
hashmap: make(map[uint64]uint64, config.initialShardSize()),
// if StatsEnabled==false，Only make(map[uint64]uint32)
hashmapStats: make(map[uint64]uint32, config.initialShardSize()),
entries: *queue.NewBytesQueue(bytesQueueInitialCapacity, maximumShardSizeInBytes, config.Verbose),
entryBuffer: make([]byte, config.MaxEntrySize+headersSizeInBytes),
onRemove: callback,
isVerbose: config.Verbose,
logger: newLogger(config.Logger),
clock: clock,
lifeWindow: uint64(config.LifeWindow.Seconds()),
statsEnabled: config.StatsEnabled,
cleanEnabled: config.CleanWindow > 0,
}
}Source: allegro/bigcache