DeviceMapper tasks in go use SetFinalizer to clean up C construct
counterparts in the C LVM library. While thats well and good, it relies
heavily on the exact interpretation of when the golang garbage collector
determines that an object is unreachable is subject to reclaimation.
While common sense would assert that for stack variables (which these DM
tasks always are), are unreachable when the stack frame in which they
are declared returns, thats not the case. According to this:
https://golang.org/pkg/runtime/#SetFinalizer
The garbage collector decides that, if a function calls into a
systemcall (which task.run() always will in LVM), and there are no
subsequent references to the task variable within that stack frame, then
it can be reclaimed. Those conditions are met in several devmapper.go
routines, and if the garbage collector runs in the middle of a
deviceMapper operation, then the task can be destroyed while the
operation is in progress, leading to crashes, failed operations and
other unpredictable behavior.
The fix is to use the KeepAlive interface:
https://golang.org/pkg/runtime/#KeepAlive
The KeepAlive method is effectively an empy reference that fools the
garbage collector into thinking that a variable is still reachable. By
adding a call to KeepAlive in the task.run() method, we can ensure that
the garbage collector won't reclaim a task object until its execution
within the deviceMapper C library is complete.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
We should check for error before reading the response (response can be
nil, and thus this would panic)
Signed-off-by: Vincent Demeester <vincent@sbr.pm>
However, do clear the directory if init or join fails, because we don't
want to leave it in a half-finished state.
Signed-off-by: Ying Li <ying.li@docker.com>
This appears to be a remnant from the CLI that is no longer imported
anywhere. Remove it from vendor.conf and the vendor directory.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
This commit exposes `Client.host` as `Client.DaemonHost()`
This allows users of the client, a CLI for example, to query the Host
that the client is attempting to contact and vary their behaviour
accordingly. For example, to allow client-side configuration of
HTTP proxy settings for a number of different docker hosts.
Signed-off-by: Dave Tucker <dt@docker.com>
Commit abd72d4008 added
a "FIXME" comment to the container "State", mentioning
that a container cannot be both "Running" and "Paused".
This comment was incorrect, because containers on
Linux actually _must_ be running in order to be
paused.
This patch adds additional information both in a
comment, and in the API documentation to clarify
that these booleans are not mutually exclusive.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
OverlayFS is supported on top of btrfs as of Linux Kernel 4.7.
Skip the hard enforcement when on kernel 4.7 or newer and
respect the kernel check override flag on older kernels.
https://btrfs.wiki.kernel.org/index.php/Changelog#By_feature
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Since this new version of the CLI resolves image digests for swarm
services by default, and we do not want integration tests to talk to
Docker Hub, update CLI tests to suppress this behavior.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
