Yes it is. For as long as you have a valid visa and an unexpired work permit, you can re-enter the country after your vacation.
However, take note of the time left on your WP upon your return as too little number of months often may lead to questions on your intent after your WP expires (i.e. risk of the returning worker staying beyond the authorized period of stay). Don't leave too little time left before returning from vacation.
Also, it would be ideal (if you intend to extend your WP) to at least have paperwork filed for an LMIA or any other available option to renew a WP - proof of that serves you good in case needed. Be prepared to answer any questions the border officers may have to ascertain your intent upon your return.
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