From db7a29716e310f2aa9e77ff2efc10fb124eb58dd Mon Sep 17 00:00:00 2001 From: Harry Zhang Date: Sun, 28 Jun 2015 22:40:53 +0800 Subject: [PATCH] Clarify that nproc is not for per container Fix ulimit nproc spec in daemon Signed-off-by: Harry Zhang --- docs/reference/commandline/daemon.md | 4 ++++ docs/reference/commandline/run.md | 16 ++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/docs/reference/commandline/daemon.md b/docs/reference/commandline/daemon.md index 4f623239f2..84648e8306 100644 --- a/docs/reference/commandline/daemon.md +++ b/docs/reference/commandline/daemon.md @@ -471,6 +471,10 @@ these defaults are not set, `ulimit` settings will be inherited, if not set on `docker run`, from the Docker daemon. Any `--ulimit` options passed to `docker run` will overwrite these defaults. +Be careful setting `nproc` with the `ulimit` flag as `nproc` is designed by Linux to +set the maximum number of processes available to a user, not to a container. For details +please check the [run](run.md) reference. + ## Miscellaneous options IP masquerading uses address translation to allow containers without a public diff --git a/docs/reference/commandline/run.md b/docs/reference/commandline/run.md index 127fafca71..5e700845a3 100644 --- a/docs/reference/commandline/run.md +++ b/docs/reference/commandline/run.md @@ -480,3 +480,19 @@ available in the default container, you can set these using the `--ulimit` flag. The values are sent to the appropriate `syscall` as they are set. Docker doesn't perform any byte conversion. Take this into account when setting the values. + +#### For `nproc` usage: + +Be careful setting `nproc` with the `ulimit` flag as `nproc` is designed by Linux to set the +maximum number of processes available to a user, not to a container. For example, start four +containers with `daemon` user: + + + docker run -d -u daemon --ulimit nproc=3 busybox top + docker run -d -u daemon --ulimit nproc=3 busybox top + docker run -d -u daemon --ulimit nproc=3 busybox top + docker run -d -u daemon --ulimit nproc=3 busybox top + +The 4th container fails and reports "[8] System error: resource temporarily unavailable" error. +This fails because the caller set `nproc=3` resulting in the first three containers using up +the three processes quota set for the `daemon` user.