fix: Scheduling the heavy database ops on bounded elastic thread pool for Ms-sql

[trishaanand]

Description

Production is seeing high number of pod restarts causing downtime. It seems to be correlated with user MS-SQL query triggers. On the hypothesis that its indeed the plugin executions causing this, it could be the datasource create taking up redis thread pool (possibly because of an upstream scheduling of a task on it)

Sample log lines displaying the behaviour (only user email removed from the logs) :
traceId=bda95acf0e182c48037214d5173d0ac9 spanId=00fdca579a517b66 - boundedElastic-13: datasourceCreate() called for MSSQL plugin.
Feb 11 05:38:05 appsmith-d6d86999-6djmx appsmith backend stdout | [2025-02-11 00:08:05,357] [lettuce-epollEventLoop-10-3] requestId=dd547055-d9bc-41ed-b7b4-03b0de691984 userEmail=<> traceId=bda95acf0e182c48037214d5173d0ac9 spanId=00fdca579a517b66 - lettuce-epollEventLoop-10-3: Connecting to SQL Server db
Feb 11 05:38:05 appsmith-d6d86999-6djmx appsmith backend stdout | [2025-02-11 00:08:05,381] [lettuce-epollEventLoop-10-3] requestId=dd547055-d9bc-41ed-b7b4-03b0de691984 userEmail=<> traceId=bda95acf0e182c48037214d5173d0ac9 spanId=00fdca579a517b66 - HikariPool-3 - Starting...
Feb 11 05:38:15 appsmith-d6d86999-6djmx appsmith backend stdout | [2025-02-11 00:08:15,346] [parallel-2] requestId=dd547055-d9bc-41ed-b7b4-03b0de691984 userEmail=<> traceId=bda95acf0e182c48037214d5173d0ac9 spanId=88ee6f7444f698dc - parallel-2: Action Query3 with id 67aa94d7b95fcb7ea3d5512c execution time : 10002 ms

This was possibly brought on by the following PR :
#38818

As part of the above PR, scheduleOn statement moved from Mono.callable() which creates its own subscription chain to outside. This could be causing the heavy database ops moving to event loop instead of bounded elastic.

Fixes #Issue Number
or
Fixes Issue URL

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Automation

/test sanity

🔍 Cypress test results

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🟢 🟢 🟢 All cypress tests have passed! 🎉 🎉 🎉
Workflow run: https://github.com/appsmithorg/appsmith/actions/runs/13265007600
Commit: 3e758fb
Cypress dashboard.
Tags: @tag.Sanity
Spec:

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Tue, 11 Feb 2025 14:53:05 UTC

Communication

Should the DevRel and Marketing teams inform users about this change?

• Yes
• No

Summary by CodeRabbit

• Refactor
  • Optimized the connection creation workflow to defer resource initialization until required. This enhancement improves the scheduling and responsiveness of establishing connections, ensuring that system resources are utilized more efficiently during runtime.

[coderabbitai]

Walkthrough

The pull request updates the datasourceCreate method in the MssqlPluginExecutor class within the MSSQL plugin. The method now wraps its execution in Mono.defer() to delay fetching the connection pool size until subscription. The logging statement for connecting to the SQL Server database has also been moved inside the Mono.defer() block, maintaining logging functionality while changing the execution context. Error handling and overall logic remain unchanged.

Changes

File(s)	Change Summary
app/server/appsmith-plugins/.../MssqlPlugin.java	Updated the datasourceCreate method in MssqlPluginExecutor: Wrapped the logic in Mono.defer() for lazy execution; moved logging inside Mono.defer().

Sequence Diagram(s)

sequenceDiagram
    participant S as Subscriber
    participant E as MssqlPluginExecutor
    participant OS as Scheduler
    S->>E: Invoke datasourceCreate()
    E->>E: Wrap execution with Mono.defer()
    E->>E: Call getMaxConnectionPoolSize() inside Mono.defer()
    E->>OS: Delegate execution with subscribeOn(scheduler)
    OS-->>E: Execute the connection creation task
    E-->>S: Return HikariDataSource

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Possibly related PRs

• fix: added configurable connection pool support for mssql #38818: Alters the datasourceCreate method to use a new configuration for the maximum connection pool size, closely relating to these changes.

Suggested labels

Task

Suggested reviewers

• NilanshBansal

Poem

In the realm where deferred calls hold sway,
The connection pool awakens in a brand-new way.
Lazy loading takes its rightful stage,
With scheduling that sets the code on a graceful page.
Here's to clean flows and runtime delight,
A symphony of code in the soft glow of night!

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📜 Recent review details

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📥 Commits

Reviewing files that changed from the base of the PR and between da66b85 and 3e758fb.

📒 Files selected for processing (1)

• app/server/appsmith-plugins/mssqlPlugin/src/main/java/com/external/plugins/MssqlPlugin.java (1 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• app/server/appsmith-plugins/mssqlPlugin/src/main/java/com/external/plugins/MssqlPlugin.java

⏰ Context from checks skipped due to timeout of 90000ms (5)

• GitHub Check: perform-test / rts-build / build
• GitHub Check: perform-test / client-build / client-build
• GitHub Check: perform-test / server-build / server-unit-tests
• GitHub Check: server-spotless / spotless-check
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