Seems that the ./tmp folder can get corrupted and then ember app fails to start via ember-cli, throwing broccoli errors, out of memory, and extremely slow build times.
eg.
Warning: failed to stat /..../tmp/broccoli_merge_trees-input_base_path-0GVrVmJW.tmp/10/.gitkeep
FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory
Seems that the ./tmp folder can get corrupted and then ember app fails to start via ember-cli, throwing broccoli errors, out of memory, and extremely slow build times.
eg.
Warning: failed to stat /..../tmp/broccoli_merge_trees-input_base_path-0GVrVmJW.tmp/10/.gitkeep
FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory
Fix is to clear the ./tmp folder.
See the following issue for confirmation of bug occurrence and fix. https://github.com/ember-cli/ember-cli/issues/7392#issuecomment-391828332
Costs of developer time to diagnose is quite large.