rate limit does not work

[Etherrrr]

Checklist

• I'm reporting a broken site support issue
• I've verified that I'm running youtube-dl version 2019.05.20
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar bug reports including closed ones
• I've read bugs section in FAQ

Verbose log

[debug] System config: []
[debug] User config: []
[debug] Custom config: ['-i', '-o', '%(uploader_id)s[%(uploader)s]/%(upload_date)s - %(title)s - (%(duration)ss) [%(resolution)s] [%(id)s].%(ext)s', '--download-archive', 'list-archive.txt', '-a', 'channel.txt', '-r', '2000K', '--match-filter', 'duration > 5', '-f', 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best', '--prefer-ffmpeg', '--merge-output-format', 'mp4', '--add-metadata', '--write-description', '--write-thumbnail', '-v']
[debug] Command-line args: ['--config-location', 'config.conf']
[debug] Batch file urls: ['https://www.youtube.com/channel/UCpmC-ZTXaVa1LHs-cJtS9aQ/', 'https://www.youtube.com/channel/UCwBMSUVMvck6EaBD0f1tHsQ/', 'https://www.youtube.com/channel/UCY32QZ2pczK5kSroH5zpDnQ/', 'https://www.youtube.com/channel/UCBIR44irWpj1eTx0ZQFofHg/', 'https://www.youtube.com/channel/UCQ7KYc1-IMQ8_Uz7XTE5DWw/', 'https://www.youtube.com/channel/UCcmSo1FpQygmtT7GzHFRh8A/']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2019.05.20
[debug] Python version 3.5.3 (CPython) - Linux-4.9.0-8-amd64-x86_64-with-debian-buster-sid
[debug] exe versions: ffmpeg 4.1.1, ffprobe 4.1.1, rtmpdump 2.4
[debug] Proxy map: {}
[debug] Invoking downloader on 'https://r5---sn-3pm7sn7s.googlevideo.com/videoplayback?id=o-AEtip3mhqQmYwFvgZWVNUl1jVE32RDSqi3vrVg-eP_qm&aitags=133%2C134%2C135%2C136%2C160%2C242%2C243%2C244%2C247%2C278&itag=136&source=youtube&requiressl=yes&mm=31%2C29&mn=sn-3pm7sn7s%2Csn-3pm76n7r&ms=au%2Crdu&mv=m&pl=37&ei=krL2XM-5IsWUigbetqTYAQ&gcr=jp&initcwndbps=11747500&mime=video%2Fmp4&gir=yes&clen=492495620&dur=4040.733&lmt=1559626697913887&mt=1559671323&fvip=6&keepalive=yes&c=WEB&txp=7316222&ip=2400%3A8500%3A1302%3A909%3A150%3A95%3A210%3A37&ipbits=0&expire=1559693042&sparams=ip%2Cipbits%2Cexpire%2Cid%2Caitags%2Csource%2Crequiressl%2Cmm%2Cmn%2Cms%2Cmv%2Cpl%2Cei%2Cgcr%2Cinitcwndbps%2Cmime%2Cgir%2Cclen%2Cdur%2Clmt&signature=E5D29E3733821E74CCAF31F5300F7127028D9B02.431085E9195DD6A5B5E4D4ECC6DE78A17D4D7BA6&key=yt8&ratebypass=yes'
[download] Destination: UCwBMSUVMvck6EaBD0f1tHsQ[綴目日傘]/20190603 - 【急遽】Nostalgic Train 　ノスタルジックトレイン【綴目日傘　新人Vtuber】 - (4041s) [1280x720] [OXdMqwde1xQ].f136.mp4
[download]   2.8% of 469.68MiB at  22.89MiB/s ETA 02:37

Description

I've limited rate to 2M with -r 2000K but it seems not work. The speed will keep about 2M/s for a while and suddenly increase to 20M/s so the network usage graph looks like a pulse graphic. Can this be fixed?

[dstftw]

You can't get ideally flat graph since the whole principle of rate limiting is to sleep between downloading blocks of data. The bigger a block the more efficiently data is processed and the more spikes graph has.
What you can do is to use fixed buffer block size.

--buffer-size SIZE               Size of download buffer (e.g. 1024 or 16K)
                                 (default is 1024)
--no-resize-buffer               Do not automatically adjust the buffer
                                 size. By default, the buffer size is
                                 automatically resized from an initial value
                                 of SIZE.

Obviously this will result in less efficient processing.