Enhancing Anacrolix/Torrent Speed: Tips for Matching Libtorrent Performance #953

abhishek-das-gupta · 2024-06-24T16:16:43Z

abhishek-das-gupta
Jun 24, 2024

Overview

We are currently replacing old libtorrent library (1.1.5) with anacrolix/torrent (v1.56.0) in order to distribute our internal binary (lets call it parcel) of size around 13 GB among all the nodes(peers) in our cluster.

Architecture:

Cluster Architecture

Within our cluster, we have master node and its workers nodes that report the state of the cluster to the master. The master generates the .torrent file. The torrent file is a trackerless torrent file. The master somewhat acts as a tracker and provides information to each peer about what other peers to communicate to during torrenting.

Torrent Architecture

For Torrenting, we have the architecture (this is independent of the torrent client library that is used) as follows:

The master node first downloads (HTTP fetch) the parcel from a remote server. The master then acts as a web seed.
Each peer gets the other peer information (host ip, port) using the Heartbeart response from the master node. Each peer then calls the API AddPeers() from the torrent client. This AddPeers() API call happens after every Heartbeat response from master to worker peer.
The torrenting starts happening between the peers (master + workers).
We also have a fallabck logic that if the parcel download doesn't complete via BitTorrent in a certain time then the fallback mechanisim is to do a HTTP download from the webseed.

Stats with libtorrent 1.1.5:

With libtorrent 1.1.5 which is quiet old, we see that it distributes the parcels in 50 node cluster in ~5 mins. This result remains same regardless of the cluster size, whether we use 5 node cluster or 50 node cluster.

Client configs

The client config for libtorrent is as follows

    settings = self.session.get_settings()
    settings['ssl_listen'] = 0
    settings['enable_upnp'] = False
    settings['enable_natpmp'] = False
    settings['enable_lsd'] = True
    settings['enable_dht'] = False

Stats with anacrolix/torrent:

But when we switch the torrent client library to anacrolix/torrent, then in a 50 node cluster, the parcel distributes completes in 26 mins and in a 5 node cluster it completes in ~7 mins.

Client configs

The client config for anacrolix/torrent is as follows:

	client := Client{}

	client.torrents = make(map[string]TorrentInfo)
	client.dataDirectory = conf.DataDirectory
	client.torrentExpiry = conf.TorrentExpiry
	client.storagePath = conf.StorageDirectory

	config := torrent.NewDefaultClientConfig()
	config.NoDHT = !conf.UseDHT
	config.DisablePEX = !conf.UsePEX
	config.DataDir = conf.DataDirectory

	// This gets filtered by the log handler in log. So getting the lowest level of log here doesn't matter.
	// Would this have a performance impact? I don't think so but we can look into that.
	config.Debug = true
	config.ListenPort = conf.Port
	config.Logger = log.CreateAnacrolixLogger()
	// This bypasses performance issues caused by https://github.com/anacrolix/torrent/discussions/916
	// config.MaxUnverifiedBytes = 0
	config.DisableIPv6 = true
	config.AlwaysWantConns = true
	config.DropDuplicatePeerIds = true
	if conf.AllowInsecureCerts {
		config.WebTransport = &http.Transport{
			TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
		}
	}
	if conf.UseDHT {
		config.PeriodicallyAnnounceTorrentsToDht = true
		config.ConfigureAnacrolixDhtServer = func(config *dht.ServerConfig) {

			// TODO: Do I want to change this to persistent storage at some point? Do we need to?
			config.PeerStore = &peer_store.InMemory{}

			config.Logger = log.CreateAnacrolixLogger()
		}
		config.DhtStartingNodes = func(network string) dht.StartingNodesGetter {
			// TODO: Is this supposed to be different in some way?
			return func() ([]dht.Addr, error) { return getStartingHosts(network) }
		}
	}
	config.Seed = true
	config.DisableTrackers = true
	client.Client, err = torrent.NewClient(config)

For both the libraries DHT is disabled. Since for historical reasons with libtorrent, we have seen unknown peers anncouncing themselves and joing the network causing multiple customer escalations.

Analysis from logs using different libraries:

With Libtorrent:

From the logs of worker node, the rate of progress( i.e totalDownloaded field) is very quick. As a result a 13.2 GB parcel download completes very quickly via torrent. Also due to this the fallback never occurs ie. (HTTP download from web seed)

[20/Jun/2024 07:32:14 +0000] 17030 WorkerThread downloader   INFO     Starting download of: http://ccycloud-1.adasgupta.root.comops.site:7180/cmf/parcel/download/CDH-7.2.18-1.cdh7.2.18.p0.51297892-el8.parcel
[20/Jun/2024 07:32:14 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=0 upload=0 state=checking_resume_data progress=0 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:16 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=463058933 upload=72056832 state=downloading progress=33081 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:18 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=910085674 upload=75153408 state=downloading progress=65017 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:20 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=1451985372 upload=99581952 state=downloading progress=103731 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:23 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=1911965445 upload=142065664 state=downloading progress=136592 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:25 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=2474367490 upload=232538112 state=downloading progress=176771 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:27 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=2974668365 upload=331350016 state=downloading progress=212513 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:29 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=3583803436 upload=441745408 state=downloading progress=256030 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:31 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=4214104730 upload=562659328 state=downloading progress=301060 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:33 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=4813310846 upload=687882240 state=downloading progress=343868 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:35 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=5289622290 upload=821870592 state=downloading progress=377896 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:37 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=5569992429 upload=965509120 state=downloading progress=397926 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:39 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=5756841073 upload=1100873728 state=downloading progress=411275 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:41 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=5923420307 upload=1241382912 state=downloading progress=423175 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:43 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=6070542187 upload=1382805901 state=downloading progress=433686 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:45 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=6236887381 upload=1515241472 state=downloading progress=445570 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:47 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=6321381352 upload=1618608128 state=downloading progress=451606 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:49 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=6440715215 upload=1710047232 state=downloading progress=460131 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:51 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=6538785002 upload=1747451904 state=downloading progress=467138 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:53 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=6992930614 upload=1809367040 state=downloading progress=499582 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:55 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=7421108402 upload=1846771712 state=downloading progress=530172 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]
[20/Jun/2024 07:32:57 +0000] 17030 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel [totalSize=13997539212 totalDownloaded=7688617385 upload=1921187840 state=downloading progress=549283 seed=[] location=/opt/cloudera/parcels/.flood/<some-parcel>.parcel]

With Anacrolix/torrent:

The logs from the same peer, shows very slow progress rate (i.e PiecesCompleted) for the same parcel size And eventually it fallbacks to HTTP download from the web seed.

[21/Jun/2024 09:19:11 +0000] 195896 WorkerThread downloader   INFO     Starting download of: http://ccycloud-1.adasgupta.root.comops.site:7180/cmf/parcel/download/<some-parcel>.parcel
[21/Jun/2024 09:19:11 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 0, 'BytesMissing': 14260886162, 'TotalBytes': 14260886162, 'BytesRead': 0, 'BytesWritten': 0, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:11 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961651.8035998 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:13 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 0, 'BytesMissing': 14260886162, 'TotalBytes': 14260886162, 'BytesRead': 0, 'BytesWritten': 0, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:13 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961653.8138583 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:15 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 0, 'BytesMissing': 14260886162, 'TotalBytes': 14260886162, 'BytesRead': 0, 'BytesWritten': 0, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:15 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961655.825992 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:17 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 0, 'BytesMissing': 14260886162, 'TotalBytes': 14260886162, 'BytesRead': 0, 'BytesWritten': 0, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:17 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961657.839617 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:19 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 0, 'BytesMissing': 14260886162, 'TotalBytes': 14260886162, 'BytesRead': 0, 'BytesWritten': 0, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:19 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961659.852322 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:21 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 0, 'BytesMissing': 14260886162, 'TotalBytes': 14260886162, 'BytesRead': 0, 'BytesWritten': 0, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:21 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961661.8653727 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:23 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 0, 'BytesMissing': 14260886162, 'TotalBytes': 14260886162, 'BytesRead': 0, 'BytesWritten': 0, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:23 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961663.877982 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:25 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 0, 'BytesMissing': 14260886162, 'TotalBytes': 14260886162, 'BytesRead': 0, 'BytesWritten': 0, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:25 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961665.8895187 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:27 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 15, 'BytesMissing': 14252186258, 'TotalBytes': 14260886162, 'BytesRead': 9121002, 'BytesWritten': 9808754, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:27 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961667.899787 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:29 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 44, 'BytesMissing': 14236211858, 'TotalBytes': 14260886162, 'BytesRead': 25670062, 'BytesWritten': 28357386, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:29 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961669.9113 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:31 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 75, 'BytesMissing': 14219401874, 'TotalBytes': 14260886162, 'BytesRead': 42891282, 'BytesWritten': 48234853, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:31 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961671.9245424 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:33 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 114, 'BytesMissing': 14199610002, 'TotalBytes': 14260886162, 'BytesRead': 63021824, 'BytesWritten': 72231234, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:33 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961673.9364014 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:35 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 156, 'BytesMissing': 14178556562, 'TotalBytes': 14260886162, 'BytesRead': 84478880, 'BytesWritten': 95194586, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:35 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961675.952003 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:37 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 216, 'BytesMissing': 14145575570, 'TotalBytes': 14260886162, 'BytesRead': 117682144, 'BytesWritten': 135538835, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:37 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961677.96288 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:39 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 317, 'BytesMissing': 14093736594, 'TotalBytes': 14260886162, 'BytesRead': 170018222, 'BytesWritten': 168176630, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:39 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961679.9735975 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:41 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 415, 'BytesMissing': 14041520786, 'TotalBytes': 14260886162, 'BytesRead': 222488086, 'BytesWritten': 215068693, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:41 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961681.9840329 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:43 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 740, 'BytesMissing': 13868079762, 'TotalBytes': 14260886162, 'BytesRead': 396369018, 'BytesWritten': 260180839, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:43 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961683.995252 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:46 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 1164, 'BytesMissing': 13644700306, 'TotalBytes': 14260886162, 'BytesRead': 619914815, 'BytesWritten': 275829148, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:46 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961686.0043845 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:48 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 1479, 'BytesMissing': 13477567122, 'TotalBytes': 14260886162, 'BytesRead': 787393796, 'BytesWritten': 313366569, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
[21/Jun/2024 09:19:48 +0000] 195896 WorkerThread downloader   INFO     self.seeding_timeout + time.time() = 1718961688.0152948 vs seed_time = 1718961651.5990217
[21/Jun/2024 09:19:50 +0000] 195896 WorkerThread downloader   INFO     Current state: <some-parcel>.parcel {'Name': '', 'TotalPieces': 27201, 'PiecesCompleted': 1889, 'BytesMissing': 13263067794, 'TotalBytes': 14260886162, 'BytesRead': 1002238144, 'BytesWritten': 340387303, 'State': 'leeching', 'Location': '/opt/cloudera/parcels/.floodix', 'Seed': []}
.
.
.
.
[21/Jun/2024 09:20:52 +0000] 195896 WorkerThread downloader   INFO     Doing HTTP_FETCH since seed_time < time.time() => 1718961651.5990217 <= 1718961652.3210127

Eventually every peer fallbacks on the webseed to download the parcel from it. This overloads the webseed.

I have enabled debug level logs on anacrolix/torrent but I don't see any thing incriminating.

Questions

Can you please help me with the following questions:

How can I determine why the torrent progress is so slow with anacrolix/torrent regardless if I use PEX or PEX + DHT?
Am I using the correct client configs for anacrolix/torrent client library? If not, can you please help in what other configs are missing? Should both PEX + DHT be used?
Is there a way to match the stats of libtorrent with anacrolix/torrent? i.e make it as performant as libtorrent
How to debug this slowness further?

TIA!

abhishek-das-gupta · 2024-06-25T17:16:58Z

abhishek-das-gupta
Jun 25, 2024
Author

Hey @anacrolix, were able to get a chance to take a look into it? Thanks

0 replies

anacrolix · 2024-06-26T10:08:29Z

anacrolix
Jun 26, 2024
Maintainer

How can I determine why the torrent progress is so slow with anacrolix/torrent regardless if I use PEX or PEX + DHT?

Your best bet is to check the status output (from WriteStatus) when a client doesn't seem to be downloading quickly. It will tell you the state of the connections to the client.

Am I using the correct client configs for anacrolix/torrent client library? If not, can you please help in what other configs are missing? Should both PEX + DHT be used?

It looks correct. PEX/DHT won't matter if you're adding peers on a heartbeat.

Is there a way to match the stats of libtorrent with anacrolix/torrent? i.e make it as performant as libtorrent

How to debug this slowness further?

Per above the status output is most helpful. If you can create a way for me to reproduce this I would be able to assist much more.

I would try with less peers (say 20), I suspect anacrolix/torrent isn't optimal when it comes to waiting for connections that have less data. Ah I see that's reflected in your testing. I would suspect connection churn to be the main issue.

2 replies

abhishek-das-gupta Jun 26, 2024
Author

@anacrolix Thanks for the repsone!

I suspect anacrolix/torrent isn't optimal when it comes to waiting for connections that have less data.

Wdym by? I didn't quite get this.

Your best bet is to check the status output (from WriteStatus) when a client doesn't seem to be downloading quickly.

I have caputered the full-status. Will attach it here in sometime.

anacrolix Jun 26, 2024
Maintainer

I haven't done any significant testing with peers that are rapidly downloading at the same time. There's a good chance will exhaust what is available from the other peer and move on to new peers rather than wait. This might be why it runs better when there are less total connections than the usual per-torrent connection limit, which I think is 40.

abhishek-das-gupta · 2024-06-27T03:20:26Z

abhishek-das-gupta
Jun 27, 2024
Author

@anacrolix during torrenting of parcel called CDH-7.2.18-1.cdh7.2.18.p300.54755622-el8.parcel (you can grep on this) , I've captured a full-status of each peer within a 5 node cluster. These statuses are captured after every 10s. Please take a look and let me know if you find anything out of the ordinary.

Note: I started capturing the status when peer1 (master node) has 100% pieces. The peer1 usually completes fast because, as I said earlier:

The master node first downloads (HTTP fetch) the parcel from a remote server. The master then acts as a web seed.

After download, the peer1 just does a copy operation to client.dataDirectory and client.StoragePath which point to same path. That is why on peer1 progress is fast. We had to do this hack otherwise the torrenting is much slower.

full-status-combined-peer1.txt
full-status-combined-peer2.txt
full-status-combined-peer3.txt
full-status-combined-peer4.txt
full-status-combined-peer5.txt

3 replies

anacrolix Jun 27, 2024
Maintainer

It looks good.

I've created a test case for this, try running https://github.com/anacrolix/torrent/tree/master/tests/peers-bootstrapping. You can play around with the parameters (like the data size, and number of clients). You can also compare it to your own set up and see if anything is missing.

abhishek-das-gupta Jun 27, 2024
Author

@anacrolix do you mean that I should deubg this test case?

anacrolix Jun 27, 2024
Maintainer

I mean if you can get that test case to reproduce your problem it will be helpful. Conversely, if anything there isn't present on your set up, and the test case works for you, maybe use it to fix your configuration.

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Enhancing Anacrolix/Torrent Speed: Tips for Matching Libtorrent Performance #953

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Enhancing Anacrolix/Torrent Speed: Tips for Matching Libtorrent Performance #953

abhishek-das-gupta Jun 24, 2024

Overview

Architecture:

Cluster Architecture

Torrent Architecture

Stats with libtorrent 1.1.5:

Client configs

Stats with anacrolix/torrent:

Client configs

Analysis from logs using different libraries:

With Libtorrent:

With Anacrolix/torrent:

Questions

Replies: 3 comments · 5 replies

abhishek-das-gupta Jun 25, 2024 Author

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