1655255 - Huge amount of heap-unclassified in main process

Status: RESOLVED INCOMPLETE

(Toolkit :: about:memory, defect)

Description

[Zhu Zihao]

Attachment: memory-report.json.gz

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:75.0) Gecko/20100101 Firefox/75.0

Steps to reproduce:

Visit some sites in Firefox safe mode. And see about:memory

Actually I visited following sites(I open each site in a new tab)

1. https://bbs.nga.cn/read.php?tid=22662758
2. https://www.youtube.com/watch?v=ChXiROKng30&list=RDeS2T9IiOYbc&index=3
3. https://www.zhihu.com/question/293518045/answer/1357201883
4. https://s0developer0mozilla0org.icopy.site/en-US/docs/Mozilla/Performance/DMD
5. https://support.mozilla.org/en-US/products/firefox?as=u&utm_source=inproduct
6. https://github.com/FelisCatus/SwitchyOmega/issues/1392

Actual results:

See a huge amount of heap-unclassified in main process, didn't decrease even I close some tabs.

Expected results:

Firefox should use less memory

Comment 1

[Zhu Zihao]

Attachment: dmd.tar

DMD profiler output

Comment 2

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Hi Zhu,

Thanks for the details. I was able to reproduce on windows 10 pro on the following versions

Firefox Nightly version 81.0a1 (2020-07-29) (64-bit)
Beta 80.0b1 (64-bit)
Release 79.0 (64-bit)

I will move this over to a component so developers can take a look over it. If is not the correct component please feel free to change it to an appropriate one.

Thanks for the report.

Best regards, Clara

Comment 3

[Andrew McCreight [:mccr8]]

Thanks for the report.

A bit chunk of the unreported memory is in this single stack:

Unreported {
11 blocks in heap block record 1 of 7,533
177,086,464 bytes (177,068,228 requested / 18,236 slop)
Individual block sizes: 58,941,440; 17,326,080; 16,986,112 x 3; 16,412,672 x 3; 585,728; 32,768; 4,096
29.84% of the heap (29.84% cumulative)
76.79% of unreported (76.79% cumulative)
Allocated at {
#01: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/bin/firefox + 0x20ad9)
#02: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x139f563)
#03: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x1378168)
#04: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x138b78c)
#05: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x13932f6)
#06: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x1395728)
#07: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x13989b0)
#08: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x16b1691)
}
}

Unfortunately, as you can see the stack is unsymbolicated. You need to run dmd.py on the log before you upload it. Are you using your own build? On OSX, you get at least some stack information without the symbolication but apparently on Linux you don't get much.

Comment 4

[Zhu Zihao]

(In reply to Andrew McCreight [:mccr8] from comment #3)

Thanks for the report.

A bit chunk of the unreported memory is in this single stack:

Unreported {
11 blocks in heap block record 1 of 7,533
177,086,464 bytes (177,068,228 requested / 18,236 slop)
Individual block sizes: 58,941,440; 17,326,080; 16,986,112 x 3; 16,412,672 x 3; 585,728; 32,768; 4,096
29.84% of the heap (29.84% cumulative)
76.79% of unreported (76.79% cumulative)
Allocated at {
#01: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/bin/firefox + 0x20ad9)
#02: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x139f563)
#03: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x1378168)
#04: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x138b78c)
#05: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x13932f6)
#06: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x1395728)
#07: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x13989b0)
#08: ??? (/gnu/store/hb8249nwjkj0lg2sh2xd0g145r8l6a0i-firefox-75.0/lib/firefox/libxul.so + 0x16b1691)
}
}

Unfortunately, as you can see the stack is unsymbolicated. You need to run dmd.py on the log before you upload it. Are you using your own build? On OSX, you get at least some stack information without the symbolication but apparently on Linux you don't get much.

Yes, I build Firefox on Guix. But unfortunately I delete old build dir so dmd.py complains that cannot found fix-stacks. How can I get executable fix-stacks? Should compile Firefox once more?

Comment 5

[Andrew McCreight [:mccr8]]

I'm not sure if the Guix build will include the right symbols or not.

Comment 6

[Zhu Zihao]

(In reply to Andrew McCreight [:mccr8] from comment #5)

I'm not sure if the Guix build will include the right symbols or not.

Oh, Guix strip symbols in build step.

I cannot reproduce this bug now. I'll report to you if I experience this again.

Comment 7

[Andrew McCreight [:mccr8]]

Thanks. Another approach would be to use the Firefox Profiler. It has a memory profiling mode that might give some insight into what was being allocated, but I haven't used it myself.

Comment 8

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:njn, could you have a look please?

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