Archive Pitfalls (GNU make)
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Make/docs/latest/Archive-Pitfalls
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11.3 Dangers When Using Archives
It is important to be careful when using parallel execution (the -j
switch; see Parallel Execution) and archives. If multiple ar
commands run at the same time on the same archive file, they will not know about each other and can corrupt the file.
Possibly a future version of make
will provide a mechanism to circumvent this problem by serializing all recipes that operate on the same archive file. But for the time being, you must either write your makefiles to avoid this problem in some other way, or not use -j
.