> For the complete documentation index, see [llms.txt](https://liuyang89116.gitbook.io/operating-system/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://liuyang89116.gitbook.io/operating-system/chapter_6_process_synchronization/61_background.md).

# 6.1 Background

1. race condition:

   A situation like this, where several processes access and manipulate the same data concurrently and the outcome of the execution depends on the particular order in which the access takes place, is called a race condition. 

![](https://1492199575-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Lpv9LvE9HvRZfFprm8G%2F-Lpv9N-nJJPlGgPdEDsP%2F-Lpv9NhKwnOfQUJ496Kb%2Fch6_01.png?generation=1569729384184148\&alt=media) ![](https://1492199575-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Lpv9LvE9HvRZfFprm8G%2F-Lpv9N-nJJPlGgPdEDsP%2F-Lpv9NhMcmtWn4eW3zAO%2Fch6_02.png?generation=1569729389314624\&alt=media) ![](https://1492199575-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Lpv9LvE9HvRZfFprm8G%2F-Lpv9N-nJJPlGgPdEDsP%2F-Lpv9NhO-o85EKHDpR0f%2Fch6_03.png?generation=1569729385172701\&alt=media)