SSH and -bash: fork: Cannot allocate memory Ubuntu , rails , Passenger, redis , sidekiq

Question

I'm running a rails app (dev server) with passenger in Amazon AWS with t2.micro instance. But i'm getting -bash: fork: Cannot allocate memory error constantly.

I'm running redis server on it with 50 sidekiq concurrency. Normally sites runs fine but when i start 2-3 sidekiq process simultaneously do do some batch process. The site take take time to redirect and eventylly crash with

502 Bad Gateway 
nginx/1.10.0

Then i have to nginx restart every to to get the site running again. This is my dev server so i don't want to put more financial resources for upgrading to t2.small (as of now, this is our last option) as this is dev servre and will be using twice in 15 days. Is there any way i can solve this otherwise? Previously i had same 120 concurrency as production but then i changed to 50. That help a bit but still memory problems.

here are few stats with htop

This stats are while the server is idle. But when i run few task with sidekiq it crashing with 502.

I check few post suggesting swap memory but not sure this is preferable with t2.micro. Is this advisable for this server setup. Here in pic you can see i don't swap memory. Is it okay yo add swap memory to tackle this issue or there is any other better option.

Answer 1

Your server has a lack of memory, to fix it:

• or: buy more operative memory

• or: mount a swap

Then try again