问题
I have a neo4j running on an ec2 instance (large, ubuntu) and I'm running some scripts on it that do lots of writings.
I noticed that after a while that those scripts run (after they wrote couple of thousand nodes) the server starting to run very slow, sometimes to the point it get absolutely stuck. another weird part - resetting the instance from this situation usually ends up in the server taking much longer than usual to init.
first I suspected that neo4j uses up all the RAM and this is a paging problem, but I've read that neo4j calculates dynamically the heap size and stack size limits. also I checked memory usage with top and it looked like most of the RAM was unused, except for Java process occasionally popping up, taking few GBs and then disappear quickly, which I assumed was neo4j.
anyway here's my question(s): do I need to config neo4j server and/or wrapper, or should I let neo4j calculate it dynamically on its own? and did someone encountered something like I described and have any idea what could cause it?
thanks!
回答1:
It's been my experience that you definitely need to tweak the memory settings to your needs. The neo4j manual has a whole section on it:
http://neo4j.com/docs/stable/configuration.html
I've not really heard of neo4j automatically adjusting to your server's memory capabilities, though just last night I did run across what seemed like a new configuration variable in conf/neo4j.properties:
# The amount of memory to use for mapping the store files, either in bytes or
# as a percentage of available memory. This will be clipped at the amount of
# free memory observed when the database starts, and automatically be rounded
# down to the nearest whole page. For example, if "500MB" is configured, but
# only 450MB of memory is free when the database starts, then the database will
# map at most 450MB. If "50%" is configured, and the system has a capacity of
# 4GB, then at most 2GB of memory will be mapped, unless the database observes
# that less than 2GB of memory is free when it starts.
#mapped_memory_total_size=50%
来源：https://stackoverflow.com/questions/27620807/neo4j-getting-slow-stuck-on-amazon-ec2