Memory load of the system is extremely high

[Shirish Morchi]

Hi,
We are testing memory engine for high update/insert rate.
There is only one table and it's completely in the memory. In our experiment we start insert/update with 100 threads, we see following message within seconds.

"“The memory load of the system is extremely high.
In order to keep the system responsive record set retrieval has been stopped.”

Any ideas as what's going on?
We have lot of memory of this box ( 4G) but table size is less than few MB.

max_heap_table_size is set to 150M.

My guess is that due to large number of threads, the CPU goes high very fast within a second and then it blocks the reads or other threads until CPU usage goes down.

Is this correct? How to debug this further? Are there any parameters we need to set about the no. of threads mysql can serve?

Thanks in advance
Shirish