Solving Concurrency Bugs Using Schedules and Imagination
Ankush Menat highlights challenges of concurrency bugs in business apps, stresses importance of addressing them. He introduces schedule diagrams as a visual debugging tool, offering a practical approach to identify and resolve concurrency issues efficiently. Menat demonstrates the effectiveness of schedule diagrams through examples, urging developers to leverage them for debugging.
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Ankush Menat discusses the challenges of dealing with concurrency bugs in business applications, emphasizing the importance of addressing these issues despite their rarity. He explains why traditional debugging methods are inefficient for concurrency bugs due to the complex nature of concurrent transactions. Menat introduces the concept of schedule diagrams as a tool to visualize and debug concurrency issues effectively. He outlines a practical approach to identifying transactions, constructing schedule diagrams, and testing hypotheses to resolve concurrency bugs. Through examples like debugging lost updates, stale cache issues, and double execution of exclusive operations, Menat demonstrates how schedule diagrams can help in understanding and resolving concurrency bugs. By leveraging imagination and careful analysis of transaction interleavings, developers can effectively tackle concurrency issues in their applications. Menat concludes by highlighting the utility of schedule diagrams in addressing various types of concurrency bugs and encourages developers to adopt this approach in their debugging processes.
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5 commentsGenerally speaking though: yes, writing it down can help A LOT, and starting with what you can see is one of those obvious-in-retrospect things that are easily forgotten when under pressure. There are often a LOT of possibilities, and getting it out of your head so you can enumerate them more precisely can super duper important. Intuition for problematic sequences to check first will come with time.
What the Shuttle library is doing is basically automatically going through all the permutations of the schedule diagrams described int his blog post.
We used it at AWS to verify the custom filesystem we wrote to power AWS S3.
If you're curious, I wrote a little tutorial on it here: https://grantslatton.com/shuttle
No better training than a great spaghetti ball of promise chains.
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