Hello everyone, I have been running an instance of Discourse for the last 2 years with Digital Ocean without any problem but since the last 2 weeks, it became very slow or unavailable most of the time. I have upgraded my hosting to the following one, it’s a bit better but still facing the same problems: Ubuntu 14.04 x64 2 vCPUs 4GB / 80GB Disk This is the output of the htop command: [image] Any idea where to start fixing this problem? Thanks a lot for your help.

top - 04:41:15 up 1 day, 25 min, 1 user, load average: 6.32, 7.70, 6.89 Tasks: 162 total, 4 running, 158 sleeping, 0 stopped, 0 zombie %Cpu(s): 64.2 us, 19.9 sy, 0.0 ni, 6.9 id, 7.7 wa, 0.0 hi, 1.3 si, 0.0 st KiB Mem : 4048268 total, 116444 free, 2742964 used, 1188860 buff/cache KiB Swap: 1048572 total, 451544 free, 597028 used. 68040 avail Mem

Given the 1m load average is nearly half what it was in the previous screenshot, and %iowait is still pretty high, I’d say you’re probably I/O constrained, likely due to swapping. Confirm with sar -W 1 whilst the system is at peak unhappiness, and then upgrade RAM.

Thanks Matt, Here is the output of the sar -W 1 (I have no idea what it is :confused: ) 04:52:49 AM pswpin/s pswpout/s 04:52:50 AM 95.00 2.00 04:52:51 AM 166.00 0.00 04:52:52 AM 40.00 0.00 04:52:53 AM 19.00 0.00 04:52:54 AM 74.00 0.00 04:52:55 AM 125.00 0.00 04:52:56 AM 247.00 0.00 04:52:57 AM 215.84 2.97 04:52:58 AM 70.00 0.00 04:52:59 AM 334.00 0.00 04:53:00 AM 390.00 0.00 04:53:01 AM 568.00 6.00 04:53:02 AM 702.00 0.00 04:53:03 AM 1047.52 5.94 04:53:04 AM 416.00 0.00 04:53:05 AM 449.00 0.00 04:53:06 AM 691.00 0.00 04:53:07 AM 772.00 6.00 04:53:08 AM 550.00 0.00 04:53:09 AM 181.00 0.00 04:53:10 AM 476.00 0.00 04:53:11 AM 348.00 0.00 04:53:12 AM 316.00 4.00 04:53:13 AM 454.00 0.00 04:53:14 AM 356.00 0.00 04:53:15 AM 911.88 7.92 04:53:16 AM 262.00 0.00 04:53:17 AM 303.00 0.00 04:53:18 AM 271.00 0.00 04:53:19 AM 284.00 6.00

The headings should give you a hint… “pages swapped in per second” and “pages swapped out per second”. Each page is (usually) 4k, so swapping in 1,000 pages in a second means you’re copying about 4MB of data off disk and into RAM. That’s gonna take a while. You’re definitely due for a RAM upgrade, or doing something to reduce RAM usage (although your unicorns aren’t exactly sitting around chatting over the sports page, so I wouldn’t recommend that).

Running this many unicorn workers on two virtual cpus that already run redis and pg does not make sense. I would run 3 workers max, and give the leftover ram to postgres.

Thanks guys. What I don’t understand is that I had 2GB RAM and it was working well, then suddenly I started to have a high load average. I already upgraded to 4GB RAM and I am still facing the same issue, how is it possible that Discourse suddenly needs so much more RAM? I also changed my app.yml with UNICORN_WORKERS: 3, it was 8 before. I am rebuilding the app now and I’ll check if there is any changes.

[תמונה] JohnDoux: I also changed my app.yml with UNICORN_WORKERS: 3 , it was 8 before. let us know how you go with the safer number

[תמונה] JohnDoux: how is it possible that Discourse suddenly needs so much more RAM? You probably started serving a whole lot more traffic.

[תמונה] mpalmer: You probably started serving a whole lot more traffic. Well actually that’s pretty much the opposite :confused: It’s a lot more quiet during summer vacation. So after 2 hours and around 30 users live: top - 06:11:09 up 1 day, 1:55, 1 user, load average: 4.09, 3.24, 2.91 Tasks: 130 total, 7 running, 123 sleeping, 0 stopped, 0 zombie %Cpu(s): 62.5 us, 26.4 sy, 0.0 ni, 1.4 id, 7.4 wa, 0.0 hi, 2.3 si, 0.0 st KiB Mem : 4048268 total, 135872 free, 1739644 used, 2172752 buff/cache KiB Swap: 1048572 total, 975084 free, 73488 used. 1763862 avail Mem [image] 06:12:12 AM pswpin/s pswpout/s 06:12:13 AM 0.00 0.00 06:12:14 AM 0.00 0.00 06:12:15 AM 0.00 0.00 06:12:16 AM 0.00 0.00 06:12:17 AM 0.00 0.00 06:12:18 AM 0.00 0.00 06:12:19 AM 0.00 0.00 06:12:20 AM 0.00 0.00 06:12:21 AM 0.00 0.00 06:12:22 AM 0.00 0.00 06:12:23 AM 0.00 6.00 06:12:24 AM 0.00 0.00 06:12:25 AM 0.00 0.00 06:12:26 AM 0.00 0.00 06:12:27 AM 0.00 5.00 06:12:28 AM 0.00 0.00 06:12:29 AM 0.00 0.00 It’s still super slow, and I keep having errors 502 on my side when I try answering a message. Some messages can be posted though.

Discourse unavailable with high load average

תמיכה

sam (Sam Saffron) 3 בספטמבר,‏ 2018,‏ 11:03am 12

How many page views are you getting? Where is the traffic coming from? Look at you nginx logs, maybe your server is under some sort of attack

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Discourse unavailable with high load average

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