Mmap failed cannot allocate memory

Has anyone seen this error before?

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mmap() failed: [12] Cannot allocate memory

mmap() failed: [12] Cannot allocate memory
PHP Fatal error: Out of memory (allocated 730865664) (tried to allocate 8192 bytes) in phar:///usr/local/bin/composer/src/Composer/DependencyResolver/GenericRule.php on line 36

Fatal error: Out of memory (allocated 730865664) (tried to allocate 8192 bytes) in phar:///usr/local/bin/composer/src/Composer/DependencyResolver/GenericRule.php on line 36