Erlang Language director
Introduction
Flexible, fast and powerful supervisor library for Erlang processes.
Remarks
Warnings
- Do not use
'count'=>infinityand elementrestartin your plan.
like:
Childspec = #{id => foo
,start => {bar, baz, [arg1, arg2]}
,plan => [restart]
,count => infinity}.
If your process did not start after crash, director will lock and retries to restart your process infinity times !
If you are using infinity for 'count', always use {restart, MiliSeconds} in 'plan' instead of restart.
- If you have plans like:
Childspec1 = #{id => foo
,start => {bar, baz}
,plan => [restart,restart,delete,wait,wait, {restart, 4000}]
,count => infinity}.
Childspec2 = #{id => foo
,start => {bar, baz}
,plan => [restart,restart,stop,wait, {restart, 20000}, restart]
,count => infinity}.
Childspec3 = #{id => foo
,start => {bar, baz}
,plan => [restart,restart,stop,wait, {restart, 20000}, restart]
,count => 0}.
Childspec4 = #{id => foo
,start => {bar, baz}
,plan => []
,count => infinity}.
The rest of delete element in Childspec1 and the rest of stop element in Childspec2 will never evaluate!
In Childspec3 you want to run your plan 0 times!
In ChildSpec4 you have not any plan to run infinity times!
- When you upgrade a release using
release_handler,release_handlercallssupervisor:get_callback_module/1for fetching its callback module.
In OTP<19get_callback_module/1uses supervisor internal state record for giving its callback module. Our director does not know about supervisor internal state record, thensupervisor:get_callback_module/1does not work with directors.
Good news is that in OTP>=19supervisor:get_callback_module/1works perfectly with directors :).
1> foo:start_link().
{ok,<0.105.0>}
2> supervisor:get_callback_module(foo_sup).
foo
3>
