elvitin / the-leaking-problem

The Leaking Problem (with the porsager/postgres library)

The Leaking Problem This issue is occurring because apparently the porsager/postgres library keeps asynchronous operations in memory without completing them. This may be causing the Deno test runner library to fail during assertion.

To simulate the problem of this project, make sure you have Deno and Docker installed.

1. Build the PostgreSQL database with:

   deno task db:build

2. Run the test with:

   deno task test

Note that the test will fail with an output like:

👈 Click here to see the error output ❌

ERRORS

leak problem test ... should not leak => https://deno.land/std@0.212.0/testing/_test_suite.ts:323:15
error: Leaking async ops:
  - 1 async operation to op_read was started in this test, but never completed. The operation was started here:
    at handleOpCallTracing (ext:core/01_core.js:535:42)
    at Object.op_read (ext:core/01_core.js:379:21)
    at TcpConn.read (ext:deno_net/01_net.js:128:26)
    at success (https://deno.land/x/postgresjs@v3.4.3/polyfills.js:97:66)
    at eventLoopTick (ext:core/01_core.js:182:7)
  - 1 async operation to sleep for a duration was started in this test, but never completed. This is often caused by not cancelling a `setTimeout` or `setInterval` call. The operation was started here:
    at handleOpCallTracing (ext:core/01_core.js:535:42)
    at op_sleep (ext:core/01_core.js:379:21)
    at runAfterTimeout (ext:deno_web/02_timers.js:234:20)
    at initializeTimer (ext:deno_web/02_timers.js:192:3)
    at setTimeout (ext:deno_web/02_timers.js:336:10)
    at Object.start (https://deno.land/x/postgresjs@v3.4.3/src/connection.js:1033:15)
    at connected (https://deno.land/x/postgresjs@v3.4.3/src/connection.js:365:17)
    at https://deno.land/x/postgresjs@v3.4.3/polyfills.js:138:30
    at Array.forEach (<anonymous>)
    at call (https://deno.land/x/postgresjs@v3.4.3/polyfills.js:138:16)

FAILURES

leak problem test ... should not leak => https://deno.land/std@0.212.0/testing/_test_suite.ts:323:15

However, note that if you turn off sanitizeOps and sanitizeResources by setting false for the sanitizers constant around line 13, the test passes again:

👈 Oops, now the test passes! ✅

running 1 test from ./main_test.ts
leak problem test ...
  should not leak ...
------- output -------
create_result:  Result(0) []
insert_result:  Result(1) [ { name: "test" } ]
drop_result:  Result(0) []
----- output end -----
  should not leak ... ok (319ms)
leak problem test ... ok (323ms)

ok | 1 passed (1 step) | 0 failed (329ms)

3. To completely remove the PostgreSQL database, run:

   deno task db:remove

Bonus: if you are on Linux, run deno task docker:print to view your Docker objects.

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Notice that the PostgreSQL driver developed by the denodrivers team does not have this issue. Check here.