Understanding Multi-process Model in Chrome

[Yuhao Zhu]

Hi All,

I am new to this community.  I basically want to understand how Chrome's multi-process/threading works.  I did take a look at a few documentations w/r to this, but they couldn't help me understand the following results which I got by running htop command in Linux.

  PID USER     PRI  NI  VIRT   RES   SHR S CPU% MEM%   TIME+  Command

14627 yuhao     20   0  268M 17292 12784 S  0.0  0.4  0:00.03  `- /opt/google/chrome/chrome --type=zygote

14718 yuhao     20   0  931M 67560 36348 S  0.0  1.8  0:10.81  |   `- /opt/google/chrome/chrome --type=renderer --enable-accelerated-2d-canvas --lang=en-US -

14723 yuhao     25   5  931M 67560 36348 S  0.0  1.8  0:00.07  |   |   `- /opt/google/chrome/chrome --type=renderer --enable-accelerated-2d-canvas --lang=en-

14722 yuhao     20   0  931M 67560 36348 S  0.0  1.8  0:00.00  |   |   `- /opt/google/chrome/chrome --type=renderer --enable-accelerated-2d-canvas --lang=en-

14721 yuhao     20   0  931M 67560 36348 S  0.0  1.8  0:00.94  |   |   `- /opt/google/chrome/chrome --type=renderer --enable-accelerated-2d-canvas --lang=en-

14629 yuhao     20   0 1131M  3132  2404 S  0.0  0.1  0:00.00  |   `- /opt/google/chrome/nacl_helper_bootstrap /opt/google/chrome/nacl_helper --at-zero

14619 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:05.62  `- /opt/google/chrome/chrome

14742 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14741 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14740 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.01  |   `- /opt/google/chrome/chrome

14739 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.01  |   `- /opt/google/chrome/chrome

14732 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14720 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14709 yuhao     20   0  379M 85516 32532 S  0.0  2.2  0:05.12  |   `- /opt/google/chrome/chrome --type=gpu-process --channel=14619.0x7fbdbbf74000.845640879 -

14711 yuhao     20   0  379M 85516 32532 S  0.0  2.2  0:00.03  |   |   `- /opt/google/chrome/chrome --type=gpu-process --channel=14619.0x7fbdbbf74000.8456408

14710 yuhao     20   0  379M 85516 32532 S  0.0  2.2  0:00.46  |   |   `- /opt/google/chrome/chrome --type=gpu-process --channel=14619.0x7fbdbbf74000.8456408

14708 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14653 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.21  |   `- /opt/google/chrome/chrome

14648 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14646 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.48  |   `- /opt/google/chrome/chrome

14645 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14644 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14643 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14642 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14641 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.01  |   `- /opt/google/chrome/chrome

14639 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:01.06  |   `- /opt/google/chrome/chrome

14638 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.05  |   `- /opt/google/chrome/chrome

14637 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14636 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.03  |   `- /opt/google/chrome/chrome

14634 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.04  |   `- /opt/google/chrome/chrome

14633 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14632 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14631 yuhao     20   0 1231M 72924 40260 S  0.0  1.9  0:00.00  |   `- /opt/google/chrome/chrome

14625 yuhao     20   0  818M  8972  2980 S  0.0  0.2  0:00.24  |   `- /opt/google/chrome/chrome

14702 yuhao     20   0  818M  8972  2980 S  0.0  0.2  0:00.00  |       `- /opt/google/chrome/chrome

Seems like there are two main processes (in bold).  What's the difference between them?   Which one is the so called "Browser process"?  Since I had only one tab opened, I guess process 14718 is the "Rendered process" for it?  But what is process 14629?  Also, for that renderer process, it has three children processes.  What are they?  Also, for process 14619, what are those children processes for?

Thanks,

Yuhao

[Nico Weber]

Hi Yuhao,

you can click the gear icon on the upper right, then Tools, then Task
Manager. Then right-click the table heading in the dialog that opens
and check "Process ID". That's an easy way to find out which process
belongs to which renderer / the browser.

Nico

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[Adam Langley]

On Thu, Dec 1, 2011 at 9:34 PM, Yuhao Zhu <yuhao.r...@gmail.com> wrote:
> I am new to this community.  I basically want to understand how Chrome's
> multi-process/threading works.  I did take a look at a few documentations
> w/r to this, but they couldn't help me understand the following results
> which I got by running htop command in Linux.

See http://code.google.com/p/chromium/wiki/LinuxZygote about the
--type=zygote process.

Cheers

AGL

[Yuhao Zhu]

Hi Nico,

In comparing with task manager, it's now clear that 14619 is the Browser process.  But what are so many children processes of it for?  It's also clear that 14718 is the Renderer process, but again what are the three children processes of it for?

Thanks,
Yuhao

[Chris Palmer]

http://blog.chromium.org/2008/09/multi-process-architecture.html

[Adam Langley]

On Thu, Dec 1, 2011 at 10:04 PM, Yuhao Zhu <yuhao.r...@gmail.com> wrote:
> In comparing with task manager, it's now clear that 14619 is the Browser
> process.  But what are so many children processes of it for?  It's also
> clear that 14718 is the Renderer process, but again what are the three
> children processes of it for?

The children of 14718 all have exactly the same memory numbers, which
means that you're probably seeing threads within the renderer process.

Cheers

AGL