init: support mutually exclusive jobs
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| upstart |
Triaged
|
Wishlist
|
Unassigned | ||
Bug Description
When two services are mutually exclusive it should not be possible to
have booth services running at the same time
We have a scenario where we have two services that are mutually exclusive.
We call them service_a and service_b. The Service a and b are defined to stop
when the other service is started(in service_a we have stop on starting_b and vice
versa).
This simple approach works as we intended. When ever we start service_b and service_a was running service_a will FIRST be stopped:
# initctl start service_a
starting service_a
started service_a
# initctl start service_b
stopping service_a
stopped service_a
starting service_b
started service_b
# initctl start service_a
stopping service_b
stopped service_b
starting service_a
started service_a
We get into trouble when we define a third service(service_c) that depends on service_b.
What we do is that we add an extra stop condition in service a (stop on starting service_c) and also add in service_b we add the extra condition (start on starting service_c)
When we start service_c we expect that FIRST service_a gets stopped and only after service_b gets started Just like in the previous example however this does not happen and we don't understand why
How to reproduce:
put service_a service_b and service_b in your directory
#issue the following command and see service_a is started
initctl start service_a
#issue the following command and see that starting service_b stops service_a
initctl start service_b
#issue the following command to have service_a running
initctl start service_a
#not start service_c and see things go wrong: first service_b is started
and only after that service_a is stopped
# initctl start service_c
starting service_b
stopping service_a
started service_b
stopped service_a
starting service_c
started service_c
| keesj (keesj) wrote | #1 |
| keesj (keesj) wrote | #2 |
| keesj (keesj) wrote | #3 |
| keesj (keesj) wrote | #4 |
| Scott James Remnant (Canonical) (canonical-scott) wrote | #5 |
| summary: |
- inconsitent dependency handling + init: support mutually exclusive jobs |
| Changed in upstart: | |
| importance: | Undecided → Wishlist |
| status: | New → Triaged |
Adding an event log
Jan 1 00:00:52 upstart: service_c goal changed from stop to start
Jan 1 00:00:52 upstart: service_c state changed from waiting to starting
Jan 1 00:00:52 upstart: event_new: Pending starting event
Jan 1 00:00:52 upstart: Handling starting event
Jan 1 00:00:52 upstart: job_register: Registered instance /com/ubuntu/
Jan 1 00:00:52 upstart: event_pending_
Jan 1 00:00:52 upstart: service_b goal changed from stop to start
Jan 1 00:00:52 upstart: service_b state changed from waiting to starting
Jan 1 00:00:52 upstart: event_new: Pending starting event
Jan 1 00:00:52 upstart: service_a goal changed from start to stop
Jan 1 00:00:52 upstart: service_a state changed from running to stopping
Jan 1 00:00:52 upstart: event_new: Pending stopping event
Jan 1 00:00:52 upstart: Handling starting event
Jan 1 00:00:52 upstart: event_finished: Finished starting event
Jan 1 00:00:52 upstart: service_b state changed from starting to pre-start
Jan 1 00:00:52 upstart: service_b pre-start process (339)
Jan 1 00:00:52 upstart: Handling stopping event
Jan 1 00:00:52 upstart: event_finished: Finished stopping event
Jan 1 00:00:52 upstart: service_a state changed from stopping to killed
Jan 1 00:00:52 upstart: service_a state changed from killed to post-stop
Jan 1 00:00:53 upstart: service_a post-stop process (342)
Jan 1 00:01:02 upstart: service_b pre-start process (339) exited normally
Jan 1 00:01:02 upstart: service_b state changed from pre-start to spawned
Jan 1 00:01:02 upstart: service_b state changed from spawned to post-start
Jan 1 00:01:02 upstart: service_b state changed from post-start to running
Jan 1 00:01:02 upstart: event_new: Pending started event
Jan 1 00:01:02 upstart: Handling started event
Jan 1 00:01:02 upstart: event_finished: Finished started event
Jan 1 00:01:03 upstart: service_a post-stop process (342) exited normally
Jan 1 00:01:03 upstart: service_a state changed from post-stop to waiting
Jan 1 00:01:03 upstart: event_new: Pending stopped event
Jan 1 00:01:03 upstart: job_change_state: Destroyed inactive instance service_a
Jan 1 00:01:03 upstart: event_finished: Finished starting event
Jan 1 00:01:03 upstart: service_c state changed from starting to pre-start
Jan 1 00:01:03 upstart: service_c pre-start process (345)
Jan 1 00:01:03 upstart: Handling stopped event
Jan 1 00:01:03 upstart: event_finished: Finished stopped event
Jan 1 00:01:13 upstart: service_c pre-start process (345) exited normally
Jan 1 00:01:13 upstart: service_c state changed from pre-start to spawned
Jan 1 00:01:13 upstart: service_c state changed from spawned to post-start
Jan 1 00:01:13 upstart: service_c state changed from post-start to running
Jan 1 00:01:13 upstart: event_new: Pending started event
Jan 1 00:01:13 upstart: Handling started event
Jan 1 00:01:13 upstart: event_finished: Finished started event