Concurrent open of connections don't work on 2.2.0 and 2.2.1 also (operation takes forever)

[Golubov Anton]

1. What versions are you using?

Oracle Database 19c

platform.platform: Windows-10-10.0.19045-SP0
sys.maxsize > 2**32: True
platform.python_version: 3.12.3

oracledb.version: 2.2.0

2. Is it an error or a hang or a crash?
   It is a hang.

3. What error(s) or behavior you are seeing?

If many connections open semultaneously then await on AsyncConnection freezes forever.

4. Does your application call init_oracle_client()?
   No, it's Thin mode.

5. Include a runnable Python script that shows the problem.

import oracledb
import asyncio

oracledb.defaults.config_dir = ' '
u = ' '
p = ' '

async def c(u, p, dsn):
    print('start')
    connection = await oracledb.connect_async(user=u,
                                              password=p,
                                              dsn=dsn)
    print('end')


async def main():
    asyncio.create_task(c(u, p, ' '))
    asyncio.create_task(c(u, p, ' '))
    await asyncio.sleep(3)

if __name__ ==  '__main__':
    asyncio.run(main())

Addition of Async.Lock synchronization solves the problem.

import oracledb
import asyncio

oracledb.defaults.config_dir = ' '
u = ' '
p = ' '

async def c(u, p, dsn, l):
    print('start')
    async with l:
        connection = await oracledb.connect_async(user=u,
                                                  password=p,
                                                  dsn=dsn)
    print('end')


async def main():
    l = asyncio.Lock()
    asyncio.create_task(c(u, p, ' ', l))
    asyncio.create_task(c(u, p, ' ', l))
    await asyncio.sleep(3)

if __name__ ==  '__main__':
    asyncio.run(main())

[Christopher Jones]

Thanks for the logging the issue.

[Anthony Tuininga]

I have pushed a patch that corrects this issue. If you are able to build from source you can verify that it works for you, too.

[Golubov Anton]

I can confirm that the error has been fixed. The test case works and the complex application also works.

[Christopher Jones]

@golubovai (and others) we'd love to get feedback on the asyncio support and understand what it lets you do that you couldn't before. Drop us a line!

[aka Eugene]

just ran into to the same issue after switching to connect_async, built from source, works as expected, no hangups on await connect_async. But... I can't (ideally) build from source/vendor on production servers... would it be possible to include this in next release? Would be greatly appreciated!

@cjbj, my use case for this is as follows:

• Automating a password change procedure across 20+ Oracle PeopleSoft environments & minimizing the time it takes
  • There is a lot of IO-bound tasks like shutting down and restarting all the domains, data-mover stuff, etc.
  • In between shutdown/restart, I need to run some SQL to affect the password change
  • My idea is to async/await everything IO-bound that I can, including database calls

real metrics: running a single update DML SQL sequentially across 20 environments takes ~8s with hot cache, while async version takes only ~0.7s.

[Anthony Tuininga]

would it be possible to include this in next release? Would be greatly appreciated!

Yes, it will be included in the upcoming release, which should be fairly soon!

[Anthony Tuininga]

This issue was corrected in version 2.3.0, which was just released.