LED traffic light on red

After years spent supporting an enterprisey desktop application with a huge codebase full of WTFs, Sammy thought he had seen all there was to be seen. He was about to find out how endlessly deep the bottom of the WTF barrel truly was.

During development, Sammy frequently had to restart said application: a surprisingly onerous process, as it took about 30 seconds each and every time to return to a usable state. Eventually, a mix of curiosity and annoyance spurred him into examining just why it took so long to start.

He began by profiling the performance. When the application first initialized, it performed 10 seconds of heavy processing. Then the CPU load dropped to 0% for a full 16 seconds. After that, it increased, pegging out one of the eight cores on Sammy's machine for 4 seconds. Finally, the application was ready to accept user input. Sammy knew that, for at least some of the time, the application was calling out to and waiting for a response from a server. That angle would have to be investigated as well.

Further digging and hair-pulling led Sammy to a buried bit of code, a Very Old Mechanism for configuring the visibility of items on the main menu. While some menu items were hard-coded, others were dynamically added by extension modules. The application administrator had the ability to hide or show any of them by switching checkboxes in a separate window.

When the application first started up, it retrieved the user's latest configuration from the server, applied it to their main menu, then sent the resulting configuration back to the server. The server, in turn, called DELETE * FROM MENU_CFG; INSERT INTO MENU_CFG (…); INSERT INTO MENU_CFG (…); …

Sammy didn't know what was the worst thing about all this. Was it the fact that the call to the server was performed synchronously for no reason? Or, that after multiple DELETE / INSERT cycles, the table of a mere 400 rows weighed more than 16 MB? When the users all came in to work at 9:00 AM and started up the application at roughly the same time, their concurrent transactions caused quite the bottleneck—and none of it was necessary. The Very Old Mechanism had been replaced with role-based configuration years earlier.

All Sammy could do was write up a change request to put in JIRA. Speaking of bottlenecks ...

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