Neil Horman
96c9cd5c39
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> (cherry picked from commit d764d8b16624e4924b3949273089f851efa0f717)
Docker CE
This repository hosts open source components of Docker Community Edition
(CE) products. The master branch serves to unify the upstream components
on a regular basis. Long-lived release branches host the code that goes
into a product version for the lifetime of the product.
This repository is solely maintained by Docker, Inc.
Unifying upstream sources
The master branch is a combination of components adapted from
different upstream git repos into a unified directory structure using the
moby-components
tool.
You can view the upstream git repos in the components.conf file. Each component is isolated into its own directory under the components directory.
The tool will import each component git history within the appropriate path.
For example, this shows a commit
is imported into the component engine from
moby/moby@a27b4b8
into the components/engine directory.
commit 5c70746915d4589a692cbe50a43cf619ed0b7152
Author: Andrea Luzzardi <aluzzardi@gmail.com>
Date: Sat Jan 19 00:13:39 2013
Initial commit
Upstream-commit: a27b4b8cb8e838d03a99b6d2b30f76bdaf2f9e5d
Component: engine
components/engine/container.go | 203 ++++++++++++++++++++++++++++...
components/engine/container_test.go | 186 ++++++++++++++++++++++++++++...
components/engine/docker.go | 112 ++++++++++++++++++++++++++++...
components/engine/docker_test.go | 175 ++++++++++++++++++++++++++++...
components/engine/filesystem.go | 52 ++++++++++++++++++++++++++++...
components/engine/filesystem_test.go | 35 +++++++++++++++++++++++++++
components/engine/lxc_template.go | 94 ++++++++++++++++++++++++++++...
components/engine/state.go | 48 ++++++++++++++++++++++++++++...
components/engine/utils.go | 115 ++++++++++++++++++++++++++++...
components/engine/utils_test.go | 126 ++++++++++++++++++++++++++++...
10 files changed, 1146 insertions(+)
Updates to master branch
Main development of new features should be directed towards the upstream
git repos. The master branch of this repo will periodically pull in new
changes from upstream to provide a point for integration.
Branching for release
When a release is started for Docker CE, a new branch will be created
from master. Branch names will be YY.MM to represent the time-based
release version of the product, e.g. 17.06.
Adding fixes to release branch
Note: every commit of a fix should affect files only within one component directory.
Fix available upstream
A PR cherry-picking the necessary commits should be created against the release branch. If the the cherry-pick cannot be applied cleanly, the logic of the fix should be ported manually.
No fix yet
First create the PR with the fix for the release branch. Once the fix has been merged, be sure to port the fix to the respective upstream git repo.
Release tags
There will be a git tag for each release candidate (RC) and general availablilty (GA) release. The tag will only point to commits on release branches.