Sync down improvements

オープン
#722 コメント 0 件 リアクション 0 件 担当者 0 名 GitHub で見る

メンテナーはふだん 1 日以内に返信

まだ誰も着手していません。

評価

難易度
5/5
見積もり時間
1週間以上
初心者へのやさしさ
8/100
issue の種類
機能追加
明瞭さ
説明が足りない
活発さ
停滞
技術スタック
cloud, python
領域
cli, cloud

調査の方向性

The sync-down download path and the --threads option are the starting points, with issue #720 as the referenced report of timeouts. The issue lists several separate proposals (per-file thread count, resumable downloads with a journal file, parallel parts, a .crdownload-style temp name) that are marked as backwards incompatible and needing a major version. Done would require a maintainer decision on which of these to pursue, so it is not a newcomer task yet.

索引モデルが issue の本文から書いたものです。

説明

enhancement

Currently large file downloads use 10 threads per file, but --threads tells the sync process how many files to process at the same time, with a default of 10 --threads it's 100 download threads in total, which can cause some of them to time out if the source cluster has a high TTFB and local storage device is not fast enough. This has been observed in #720, but also others.

Configurability of download thread count should be improved.

Continuing broken downloads should be implemented somehow. As of today the native B2 server API does not allow for checking of checksums on the cloud side. Most likely it requires a separate "journal" file that would be flushed whenever we write a block, to indicate which parts of the file are written correctly (in case we use parallel downloader), or up to which point the file is correct.

B2 integration checklist says:

Downloads over 200MB should be split into parts and downloaded simultaneously. Once all parts are downloaded, the large file should be stitched together.
out of concern for performance, I think, but maybe if we have multiple download operations running simultaneously (due to sync down of many big files), then splitting them to smaller chunks is not good for anyone.

Finally, if a download operation is interrupted forcibly somehow, the client has a file with correct extension, maybe even correct size, but not necessarily correct data. In order to avoid this, Google Chrome adds a .crdownload extra extension to a file to indicate is has not been finished yet.

Most of those changes are backwards incompatible and would require a major version increase, so they should probably be done together.

主要言語
Python
スター
638
フォーク
138
平均マージ
8時間 27分
マージ済み PR(30日)
8

環境構築

はじめの一歩

  1. issue を最後まで読み、次にプロジェクトのコントリビューションガイドを読みます。
  2. 着手することを issue にコメントします — 二人が同じ作業をするのを防げます。
  3. リポジトリをフォークし、ブランチを切って変更します。
  4. issue 番号を参照したプルリクエストを送ります。

Backblaze/B2_Command_Line_Tool のほかの issue

Backblaze/B2_Command_Line_Tool の issue をすべて見る

似ている issue

Python の issue をもっと見る

新しい issue をメールで受け取る

初心者向けの GitHub issue を短くまとめたダイジェスト。