The method {{{ipaclient.remote_plugins.schema.Schema._write_schema}}} is not multiprocess concurrency safe. If multiple processes happen to fetch and update the API schema at the same time, they old write to the same file at the same time. I ran into the issue when I was stress-testing vault with multiple parallel processes.

Instead of writing to final file, the writer should use safe atomic operations:

• write to a temporary file with random and unique file names in the destination directory
• optionally flush and fdatasync the fd
• close the temp file
• use atomic os.rename() to rename the temp file to permanent file.

This operation is safe even if multiple processes create the schema cache at the same time. They all end up to write to different files but only the last rename will win.