4.2: cluster - after some stress tests (3 hours), the platform froze

Before going home last evening, I launched a stress test on my 4.2 cluster (50 users in live mode and 25 in edit mode)... Seems like around 20h00 yesterday evening (so 3 hours after the begionning of the test), the platform froze (cf thread dump). The site is currently unavailable on both nodes of the environement.