pull_subquery_card() hangs in block_for_data_from_db() and never triggers do_post

Hi team,

First of all, thank you for the great work on PilotScope and for making it publicly available—this is a very impressive and valuable tool!

I'm encountering an issue when trying to run `benchmark_subquery` in the PRICE project that uses your work for generating workloads, and I hope you can help clarify or provide suggestions for debugging.

### Problem
When running the workload—specifically calling `pull_subquery_card()`—the process hangs in the `block_for_data_from_db()` function inside `HttpInteractorReceiver.py` and eventually times out.

Interestingly, when I run `pull_record()` instead, I do get the expected result.

### What I've tried
- Tested on **two separate servers** to rule out environment-specific problems.
- Verified that **all dependencies are installed** correctly (the way that you said)
- Confirmed from **PostgreSQL logs** that the query request is indeed received successfully.
- Verified that the relevant **ports are open and functional**.
- Did some debugging and noticed that:
- The `do_post()` method in `HttpInteractorReceiver.py` **never gets called**.
- The receiver seems to be waiting indefinitely for a response that never comes.

### Request
Do you have any idea what might be causing this behavior?
Any suggestions for debugging or known issues in this area would be much appreciated.

Thanks again for the excellent work—and looking forward to any guidance you can provide!

Best regards

Start in HttpInteractorReceiver.py by tracing pull_subquery_card() through block_for_data_from_db() and compare that path with pull_record(), which returns successfully. Check the reported point where do_post() is never called and correlate it with the PostgreSQL logs and timeout behavior. Done means the subquery workload completes without hanging and do_post() is reached as expected.

Written by the indexing model from the issue text.