Bug 1103595

Summary: Docker daemon uses 100 % CPU during download during build
Product: [Fedora] Fedora Reporter: Jan Pazdziora (Red Hat) <jpazdziora>
Component: docker-ioAssignee: Lokesh Mandvekar <lsm5>
Status: CLOSED CURRENTRELEASE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 20CC: admiller, dwalsh, golang-updates, jkeck, jpazdziora, lsm5, mattdm, mgoldman, s, vbatts
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2014-06-23 15:17:55 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Jan Pazdziora (Red Hat) 2014-06-02 07:35:52 UTC 
Description of problem:

I run docker build which downloads images. While this happens, the docker daemon is using up-to 100 % CPU when it probably does not have that much work to do, given the speed of my network.

Version-Release number of selected component (if applicable):

# rpm -qf /usr/bin/docker
docker-io-0.11.1-7.fc20.x86_64

How reproducible:

Seen once.

Steps to Reproduce:
1. ( echo FROM fedora:20 ; ADD testfile /bin/testfile ) > Dockerfile
2. docker build -t test-1 .
3. In other terminal, observe top while the images are being downloaded.

Actual results:

# docker build -t test-1 .
Uploading context 3.584 kB
Uploading context 
Step 0 : FROM fedora:20
Pulling repository fedora
4f4eba4c47b8: Downloading [===========================================>       ] 101.4 MB/115.9 MB 5s
511136ea3c5a: Download complete 
8c982ec5ea99: Download complete 

and while the download is running

# top

top - 03:26:45 up 6 days, 36 min,  2 users,  load average: 0.58, 0.30, 0.17
Tasks: 153 total,   2 running, 151 sleeping,   0 stopped,   0 zombie
%Cpu(s): 14.8 us, 11.3 sy,  0.0 ni, 43.9 id, 27.1 wa,  1.8 hi,  1.1 si,  0.0 st
KiB Mem:   8160392 total,  4357084 used,  3803308 free,   176932 buffers
KiB Swap:  8273916 total,        0 used,  8273916 free,  3490916 cached

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND     
16112 root      20   0  588820  35144   7144 S  97.3  0.4   1:31.79 docker      
16119 root       0 -20       0      0      0 S   3.6  0.0   0:04.29 loop0   

and

# ps axuw | grep docker
root     16112  7.6  0.4 588820 36176 ?        Ssl  03:05   1:37 /usr/bin/docker -d --selinux-enabled
root     16287  0.3  0.0 284764  5308 pts/0    Sl+  03:26   0:00 docker build -t test-1 .
root     16341  0.0  0.0 112668   964 pts/1    S+   03:26   0:00 grep --color=auto docker

Expected results:

I'd expect the daemon not consuming 100 % CPU when the only action happening is download of images on fairly slow line.

Additional info:
Comment 1 Daniel Walsh 2014-06-03 20:49:54 UTC 
It is copying the image over the network.  I would guess this is just the daemon using as much CPU as possible while downloading.
Comment 2 Jan Pazdziora (Red Hat) 2014-06-18 07:08:58 UTC 
What information do you need?
Comment 3 Daniel Walsh 2014-06-18 12:51:06 UTC 
Was it during the download, or continuous?  Can you try again with docker-1.0  TO see if the problem persists.
Comment 4 Jan Pazdziora (Red Hat) 2014-06-18 14:12:53 UTC 
Yes, it was during the download. Which is why I was suspicious because the download speed was not that great to warrant 100 % CPU utilization.

I will check with 1.0.
Comment 5 Jan Pazdziora (Red Hat) 2014-06-23 15:17:55 UTC 
(In reply to Daniel Walsh from comment #3)
> Was it during the download, or continuous?  Can you try again with
> docker-1.0  TO see if the problem persists.

With docker-io-1.0.0-1.fc20.x86_64, the issues does not manifest itself.