There was no guarantee that the SELECT FOR KEY SHARE queries actually
run in parallel. With unlucky timing, one query might finish before
the next one starts, so that the server doesn't need to create a
multixact. I got a failure like that on the CI:
batch_others/test_multixact.py:56: in test_multixact
assert(int(next_multixact_id) > int(next_multixact_id_old))
E AssertionError: assert 1 > 1
E + where 1 = int('1')
E + and 1 = int('1')
This could be reproduced by adding a random sleep in the runQuery
function, to make each query run at different times.
To fix, keep the transactions open after running the queries, so that
they will surely be open concurrently. With that, we can run the
queries serially, and don't need the 'multiprocessing' module anymore.
Fixes https://github.com/zenithdb/zenith/issues/196
* Add ancestor_id to pg_list->branch_list output of pageserver.
* Display branching point (LSN) for each non-root branch.
* Add tests for `zenith branch`.
- The 'pageserver' fixture now sets up the repository and starts up
the Page Server automatically. In other words, the 'pageserver'
fixture provides a Page Server that's up and running and ready to
use in tests.
- The 'pageserver' fixture now also creates a branch called 'empty',
right after initializing the repository. By convention, all the
tests start by createing a new branch off 'empty' for the test. This
allows running all the tests against the same Page Server
concurrently. (I haven't tested that though. pytest doensn't
provide an option to run tests in parallel but there are extensions
for that.)
- Remove the 'zen_simple' fixture. Now that 'pageserver' provides
server that's up and running, it's pretty simple to use the
'pageserver' and 'postgres' fixtures directly.
- Don't assume host name or ports in the tests. They now use the
fields in the fixtures for that. That allows assigning the ports
dynamically, making it possible to run multiple page servers in
parallel, or running the tests in parallel with another page
server. This commit still hard codes the Page Server's port in the
fixture, though, so more work is needed to actually make it
possible.
- I made some changes to the 'postgres' fixture in commit 532918e13d,
which broke the other tests. Fix them.
- Divide the tests into two "batches" of roughly equal runtime, which
can be run in parallel
- Merge the 'test_file' and 'test_filter' options in CircleCI config
into one 'test_selection' option, for simplicity.
