BUG：Abnormal high CPU usage

[xczh]

When I used it with dnsmasq for a while, I observed abnormal high CPU usage, as shown in the screenshot.

I use strace to try to track PID 13544, which shows that the program is blocking the waitid system call, and there is no other information. Through the top command, I learned that CPU time is basically spent in us state, not sys state.

This situation has been going on for 24 hours, and it doesn't seem to be a problem of 'dnsmasq'. What happened to 'webproc'?

[xczh]

@jpillora I need help, thanks :)

[jpillora]

Could be related to log processing. Is dnsmasq logging heavily?

On Thu, 18 Feb 2021 at 7:54 pm Chris Winnie notifications@github.com wrote:

When I used it with dnsmasq for a while, I observed abnormal high CPU usage, as shown in the screenshot.

[image: image] https://user-images.githubusercontent.com/12578552/108330891-1f47bf80-7209-11eb-85d9-ed938653c8c0.png

I use strace to try to track PID 13544, which shows that the program is blocking the waitid system call, and there is no other information. Through the top command, I learned that CPU time is basically spent in us state, not sys state.

This situation has been going on for 24 hours, and it doesn't seem to be a problem of 'dnsmasq'. What happened to 'webproc'?

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[xczh]

No, the log frequency is about 1 line/s.

And this phenomenon is only recently. Before, I used v0.3.0 version to run stably for nearly a year, and did not find this problem. I upgraded to version v0.4.0 the day before yesterday, and this problem occurred two days after running.

[xczh]

In order to eliminate the problem of dnsmasq, I rerun the program. I used mpstat 1 to print out the CPU utilization per second, and found a very interesting phenomenon.

# webproc -c /etc/dnsmasq.conf -p 80 --user test --pass 123456 -- mpstat 1

After the program runs for 2 minutes, the CPU utilization rate is still as high as 100%.

These are mpstat output:

⁣09:22:39     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:22:40     all    0.00    0.00    0.00    0.00    0.25    0.25    0.00    0.00   99.50
⁣
⁣09:22:40     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:22:41     all    0.00    0.00    0.25    0.00    0.00    0.00    0.00    0.00   99.75
⁣
⁣09:22:41     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:22:42     all    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00

......

⁣09:24:24     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:25     all    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
⁣
⁣09:24:25     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:26     all    0.00    0.00    0.00    0.00    0.00    0.25    0.00    0.00   99.75
⁣
⁣09:24:26     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:27     all    0.00    0.00    0.25    0.00    0.00    0.00    0.00    0.00   99.75
⁣
⁣09:24:27     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:28     all    4.52    0.00    0.50    0.00    0.25    0.00    0.00    0.00   94.72
⁣
⁣09:24:28     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:29     all   16.08    0.00    1.51    0.00    0.50    0.50    0.00    0.00   81.41
⁣
⁣09:24:29     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:30     all    0.25    0.00    0.00    0.00    0.25    0.00    0.00    0.00   99.50
⁣
⁣09:24:30     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:31     all   18.30    0.00    3.51    0.00    0.50    0.00    0.00    0.00   77.69
⁣
⁣09:24:31     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:32     all   17.97    0.00    0.51    0.00    0.51    0.00    0.00    0.00   81.01
⁣
⁣09:24:32     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:33     all   17.88    0.00    0.76    0.00    0.76    0.25    0.00    0.00   80.35
⁣
⁣09:24:33     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:34     all   18.18    0.00    0.76    0.00    0.51    0.00    0.00    0.00   80.56
⁣
⁣09:24:34     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:35     all   19.10    0.00    0.50    0.00    0.75    0.00    0.00    0.00   79.65
⁣
⁣09:24:35     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:36     all   19.24    0.00    0.76    0.00    0.51    0.00    0.00    0.00   79.49
⁣
⁣09:24:36     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
⁣09:24:37     all   18.94    0.00    0.76    0.00    0.76    0.00    0.00    0.00   79.55

Since then, CPU usage has remained at this level.

@jpillora

[jpillora]

Are you streaming logs on the web frontend? Does this happen when webproc has no clients?

On 18 Feb 2021 at 8:33:41 pm, Chris Winnie notifications@github.com wrote:

In order to eliminate the problem of dnsmasq, I rerun the program. I used mpstat 1 to print out the CPU utilization per second, and found a very interesting phenomenon.

webproc -c /etc/dnsmasq.conf -p 80 --user test --pass 123456 -- mpstat 1

[image: image] https://user-images.githubusercontent.com/12578552/108336018-903da600-720e-11eb-8b4a-9cf3559f67d7.png

After the program runs for 2 minutes, the CPU utilization rate is still as high as 100%.

These are mpstat output:

⁣09:22:39 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:22:40 all 0.00 0.00 0.00 0.00 0.25 0.25 0.00 0.00 99.50

⁣

⁣09:22:40 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:22:41 all 0.00 0.00 0.25 0.00 0.00 0.00 0.00 0.00 99.75

⁣

⁣09:22:41 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:22:42 all 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00

......

⁣09:24:24 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:25 all 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00

⁣

⁣09:24:25 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:26 all 0.00 0.00 0.00 0.00 0.00 0.25 0.00 0.00 99.75

⁣

⁣09:24:26 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:27 all 0.00 0.00 0.25 0.00 0.00 0.00 0.00 0.00 99.75

⁣

⁣09:24:27 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:28 all 4.52 0.00 0.50 0.00 0.25 0.00 0.00 0.00 94.72

⁣

⁣09:24:28 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:29 all 16.08 0.00 1.51 0.00 0.50 0.50 0.00 0.00 81.41

⁣

⁣09:24:29 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:30 all 0.25 0.00 0.00 0.00 0.25 0.00 0.00 0.00 99.50

⁣

⁣09:24:30 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:31 all 18.30 0.00 3.51 0.00 0.50 0.00 0.00 0.00 77.69

⁣

⁣09:24:31 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:32 all 17.97 0.00 0.51 0.00 0.51 0.00 0.00 0.00 81.01

⁣

⁣09:24:32 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:33 all 17.88 0.00 0.76 0.00 0.76 0.25 0.00 0.00 80.35

⁣

⁣09:24:33 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:34 all 18.18 0.00 0.76 0.00 0.51 0.00 0.00 0.00 80.56

⁣

⁣09:24:34 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:35 all 19.10 0.00 0.50 0.00 0.75 0.00 0.00 0.00 79.65

⁣

⁣09:24:35 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:36 all 19.24 0.00 0.76 0.00 0.51 0.00 0.00 0.00 79.49

⁣

⁣09:24:36 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle

⁣09:24:37 all 18.94 0.00 0.76 0.00 0.76 0.00 0.00 0.00 79.55

Since then, CPU usage has remained at this level.

@jpillora https://github.com/jpillora

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[xczh]

I just executed this command:

webproc -c /etc/dnsmasq.conf -p 80 --user test --pass 123456 -- mpstat 1

and then open the browser to access: http://localhost.

mpstat 1 prints CPU usage every second.

[jpillora]

If you don't open the browser, does CPU still go high?

On 18 Feb 2021 at 8:50:00 pm, Chris Winnie notifications@github.com wrote:

I just executed this command:

webproc - C / etc/ dnsmasq.conf -P 80 -- user test -- pass 123456 -- mpstat 1

and then open the browser to access: http://localhost.

mpstat 1 prints CPU usage every second.

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[xczh]

Exactly. I find that if I don't open the browser, the CPU usage is always less than 0.5%. Once you open your browser, it's 100% in a flash. But why is that?

Will JavaScript scripts affect the CPU utilization of the server?

[jpillora]

This means it’s a bug with the data synchronisation library (velox). The server is looping somewhere... most likely will need a new release which includes debugging API endpoints to investigate further

What os/arch are you running?

On Thu, 18 Feb 2021 at 9:02 pm Chris Winnie notifications@github.com wrote:

Exactly. I find that if I don't open the browser, the CPU usage is always less than 0.5%. Once you open your browser, it's 100% in a flash. But why is that?

Will JavaScript scripts affect the CPU utilization of the server?

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[xczh]

Fedora 33, amd64

[jpillora]

As a work around, could you try setting max lines to something low, maybe 100?

On Thu, 18 Feb 2021 at 9:23 pm Chris Winnie notifications@github.com wrote:

Fedora 33, amd64

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[xczh]

In addition, I suggest adding the net/http/pprof HTTP endpoint to facilitate troubleshooting.

[xczh]

It seems that this problem does not exist in v0.3.0. Can I switch back to the old version? What are the disadvantages?

[jpillora]

Shouldn’t be too different, been a long time, I’d need to look at the diff

On Thu, 18 Feb 2021 at 9:26 pm Chris Winnie notifications@github.com wrote:

It seems that this problem does not exist in v0.3.0. Can I switch back to the old version? What are the disadvantages?

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[xczh]

I was wrong. Just now, I spent more than an hour retesting the v0.3.0 version and found that the leak still exists. CPU usage is increasing at a very slow rate, but it does continue to increase. This can lead to problems that are hard to detect and I've ignored in the past year.

In the version of v0.4.0, the CPU consumption increases rapidly when using the browser to access the page, which leads to the problem being found quickly.

This problem looks SERIOUS and needs to be fixed. Before the problem is solved, I think I can only disable webproc.

Or are there any effective measures?

[jpillora]

As a work around, could you try setting max lines to something low, maybe 100?

On 18 Feb 2021 at 10:53:01 pm, Chris Winnie notifications@github.com wrote:

[image: image] https://user-images.githubusercontent.com/12578552/108353049-a35a7100-7222-11eb-9ffe-2057e212336c.png

I was wrong. Just now, I spent more than an hour retesting the v0.3.0 version and found that the leak still exists. CPU usage is increasing at a very slow rate, but it does continue to increase. This can lead to problems that are hard to detect and I've ignored in the past year.

In the version of v0.4.0, the CPU consumption increases rapidly when using the browser to access the page, which leads to the problem being found quickly.

This problem looks SERIOUS and needs to be fixed. Before the problem is solved, I think I can only disable webproc.

Or are there any effective measures?

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[Schwobaland]

I have the same problem. Setting the max-lines to 100 didn't help...

[jpillora]

OS arch?

On Tue, 9 Mar 2021 at 10:29 pm Schwobaland notifications@github.com wrote:

I have the same problem. Setting the max-lines to 100 didn't help...

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[Schwobaland]

Arm64. What helped, was disabling the logs for the webui - with the downside of missing logs in the webui. -l proxy

By the way - thanks for creating webproc!!

[rinex20]

I had the same issue like above. @jpillora ubuntu x86_64.

[rinex20]

I had the same issue like above. @jpillora ubuntu x86_64.

finally, downgrade to 0.3.3 to fix this high cpu usage.

[ThorstenKunz]

Same issue with 0.4.0. I added "-l proxy" and that solved it. Running on Linux raspberrypi 5.4.0-1066-raspi #76-Ubuntu SMP PREEMPT Mon Jun 27 11:02:52 UTC 2022 aarch64 aarch64 aarch64 GNU/Linux