mirror of
https://github.com/haproxy/haproxy.git
synced 2026-02-10 06:13:20 -05:00
HAProxy - Load balancer
ef6ca67176
soft-stop was not explicitly handled in event_hdl API.
Because of this, event_hdl was causing some leaks on deinit paths.
Moreover, a task responsible for handling events could require some
additional cleanups (ie: advanced async task), and as the task was not
protected against abort when soft-stopping, such cleanup could not be
performed unless the task itself implements the required protections,
which is not optimal.
Consider this new approach:
'jobs' global variable is incremented whenever an async subscription is
created to prevent the related task from being aborted before the task
acknowledges the final END event.
Once the END event is acknowledged and freed by the task, the 'jobs'
variable is decremented, and the deinit process may continue (including
the abortion of remaining tasks not guarded by the 'jobs' variable).
To do this, a new global mt_list is required: known_event_hdl_sub_list
This list tracks the known (initialized) subscription lists within the
process.
sub_lists are automatically added to the "known" list when calling
event_hdl_sub_list_init(), and are removed from the list with
event_hdl_sub_list_destroy().
This allows us to implement a global thread-safe event_hdl deinit()
function that is automatically called on soft-stop thanks to signal(0).
When event_hdl deinit() is initiated, we simply iterate against the known
subscription lists to destroy them.
event_hdl_subscribe_ptr() was slightly modified to make sure that a sub_list
may not accept new subscriptions once it is destroyed (removed from the
known list)
This can occur between the time the soft-stop is initiated (signal(0)) and
haproxy actually enters in the deinit() function (once tasks are either
finished or aborted and other threads already joined).
It is safe to destroy() the subscription list multiple times as long
as the pointer is still valid (ie: first on soft-stop when handling
the '0' signal, then from regular deinit() path): the function does
nothing if the subscription list is already removed.
We partially reverted "BUG/MINOR: event_hdl: make event_hdl_subscribe thread-safe"
since we can use parent mt_list locking instead of a dedicated lock to make
the check gainst duplicate subscription ID.
(insert_lock is not useful anymore)
The check in itself is not changed, only the locking method.
sizeof(event_hdl_sub_list) slightly increases: from 24 bits to 32bits due
to the additional mt_list struct within it.
With that said, having thread-safe list to store known subscription lists
is a good thing: it could help to implement additional management
logic for subcription lists and could be useful to add some stats or
debugging tools in the future.
If
|
||
|---|---|---|
| .github | ||
| addons | ||
| admin | ||
| dev | ||
| doc | ||
| examples | ||
| include | ||
| reg-tests | ||
| scripts | ||
| src | ||
| tests | ||
| .cirrus.yml | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .travis.yml | ||
| BRANCHES | ||
| CHANGELOG | ||
| CONTRIBUTING | ||
| INSTALL | ||
| LICENSE | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
| SUBVERS | ||
| VERDATE | ||
| VERSION | ||
The HAProxy documentation has been split into a number of different files for ease of use. Please refer to the following files depending on what you're looking for : - INSTALL for instructions on how to build and install HAProxy - BRANCHES to understand the project's life cycle and what version to use - LICENSE for the project's license - CONTRIBUTING for the process to follow to submit contributions The more detailed documentation is located into the doc/ directory : - doc/intro.txt for a quick introduction on HAProxy - doc/configuration.txt for the configuration's reference manual - doc/lua.txt for the Lua's reference manual - doc/SPOE.txt for how to use the SPOE engine - doc/network-namespaces.txt for how to use network namespaces under Linux - doc/management.txt for the management guide - doc/regression-testing.txt for how to use the regression testing suite - doc/peers.txt for the peers protocol reference - doc/coding-style.txt for how to adopt HAProxy's coding style - doc/internals for developer-specific documentation (not all up to date)