[Fixed][P0][Performance][RootTicket][CZGithub SlowScrolling ] CZWebImage consumes 83.2% CPU time - CZDiskCacheManager.flushCachedItemsDictToDisk().

[geekaurora]

My Doc

Description

• CZGithubReactAppKit - Slow when scrolling - CZWebImage.
• Even scroll at same screen - scroll up/down. (As it updates visitedDate for each image)

Sub ticket

• [Won't Fix][P2][Performance] CZDiskCacheManager.setCacheFile() - WriteFile threadsafety ioQueue.async(flags: .barrier) #38

Reasons: CZDiskCacheManager in CZHttpFile package

• CZDiskCacheManager.flushCachedItemsDictToDisk(): Without flushCachedItemsDictToDisk() = 60 FPS

CZWebImage - Call Stack

1. Write fileInfo - setCachedItemsDict

• CZHttpFileManager.downloadFile() // OK
• CZDiskCacheManager.getCachedFile(withUrl:) // OK
• update visiteData // OK: removed
• CZDiskCacheManager.setCachedItemsDict(key:subkey:value:skipIfKeyNotExists:) // OK: DebounceTaskScheduler
• CZDiskCacheManager.cachedItemsDictLockWrite(:) // OK: DebounceTaskScheduler
• CZMutexLock.writeLock(.barrier) (Block main thread) // OK: DebounceTaskScheduler
• flushCachedItemsDictToDisk() (DiskIO: shouldn't write for each cache file getting - visitDate: batchUpdate) // OK: DebounceTaskScheduler

2. Write downloaded file - with .barrier async: [Risky][Won't Fix] write file with .atomic option.

Sub ticket: #38

Investigation

• Remove CZWebImage: 60FPS (Always: even load more)

Solutions

Without flushCachedItemsDictToDisk(): 60 FPS

1. DebounceTaskScheduler - cachedItemsDict: merges the same tasks with gap and only executes the last task.
2. Write file: remove .barrier - CZDiskCacheManager.ioQueue.async()

• Avoid blocking: writing files is very frequent

3. Flag shouldEnableCachedItemsDict: indicates whether to save cached file information. e.g. url, size. Defaults to false.

• CZWebImage = false, CZHttpFile = true - large files.

Added back

• [CZHttpFile] httpManager.cancelTask(with: url) // 2022.11.25

[Risky?] Not Added Back!!

• Write downloaded file with .barrier async - [Risky][Won't Fix] write file with .atomic option.
  Sub ticket: [Won't Fix][P2][Performance] CZDiskCacheManager.setCacheFile() - WriteFile threadsafety ioQueue.async(flags: .barrier) #38

Other improvements

• CZHttpFileManager.downloadFile
  • getCache()
  • ioQueue.async(): it was sync() - block main thread when get cache.
• ioQueue: QoS - from .userInitiated to .default (Faster: image slower)

Sub improvements

• Remove visitedDate - clean cache with createdDate

No need

• cachedItemsDict file.write(): Async - ioQueue (separate serialQueue?)

[geekaurora]

Xcode Profile logs

1.33 s 83.2% 0 s 0x1024aa84e CZWebImage
CZHttpFile
CZUtils