How to debug memory consumption of the Bukkit server?

For some time now (since 1.4.x), we've had a problem with memory consumption on our server. The symptoms are such that the consumption slowly creeps up and never goes down, even with NO players on the server. In the end, it reaches 100% of our server's allocated memory and that's when it starts to affect the server negatively. Crashes in this situation are frequent. A restart always brings the memory consumption back to the initial value - and then it starts to creep up again.

Now I'm aware that this might be a bad memory leak in some of the plugins we're using. Another possibility is that one (or few) of the plugins load chunks into memory and never releases them. To investigate this further, we'd need some tools. For this reason, I'm asking for help on these:

1. Is there a way (or plugin) to report the current memory consumption of each plugin?
2. Is there a way (or plugin) to tell me how many chunks the server has loaded currently?

Further info: we are renting our server and do not have any real Java profiling tools available to investigate this.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

With java, and without profiling tools it is almost impossible to do so.. The best you can do is trial and error by removing plugins and tweaking settings one at a time.