Possible memory leak

Problem

So there could be a possible memory leak on Express v4.x We have been in constant communications with the Google App Engine team to troubleshoot our servers crashing thought to high memory usage and appears to be a memory leak in Express. Our API is served by Express 4.14.0, the screenshot aboce is an instance only receiving 6 health checks from Google every 5 seconds and within a few days, it crashes because of high memory usage. We thought that was a problem within our base code but we decided to throw a Hello World from Google App Engine which is using only a dependency which is Express 4.15.4 and the same result (graph below). Both instances received health checks from Google every 5 seconds to report their up time and send CPU usage, memory usage, disk usage to Stackdriver The Google Cloud support team was able to reproduce the issue outside of the GCP with the Hello World app and saw the heaps stack size staying consisitent but the overall process memory growing. Since the only dependencies we were using was express we have decided to open an issue. Here is the memory graph that they had. We are currently using Node v6.9.11 in our production.