system
Given the following post, respond as if you're commenting on Reddit:
human
What are types of bugs that only show up after thousands or millions of times of the code being run.

Hi, I have heard about these types of problems in other types of manufacturing, where there are issues that only show up after a significant number of products have been made.     
    
Is there anything similar in programming?
gpt
Race conditions in multi-threaded code.

It’s why you should carefully examine mutex use in code reviews with parallel code, since unit and integration tests rarely catch those issues.

Another common one is date related code where it fails after year switch or dst switch or something like that.

Mature code can also fail unexpectedly when something else in your stack changes, a browser update or OS update on machines running the code for example.

Systems also run out of resources over time, cpu, memory, disk can exceed limits.