On Oct 25, 5:31 am, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > Yet another hosting query. > > I've been looking for a hosting provider for a few days, looked > through the old threads and the recommended hosts at webpy.org/hosts > and have tentatively settled on grokthis with one of their VPS > packages. Does anyone have any experience with them? Was it good, easy > to set up? Does anyone particularly recommend a different host?
I am still yet to get my head around how these VPS systems are configured, but one thing to be a bit mindful of when selecting a VPS, is how your memory usage limit is determined. If one has a standalone UNIX system, in general one looks at resident private memory (RSS) and resident shared memory (SHR) and as a gauge of how much memory processes are taking. The amount of overall virtual memory that a process could use isn't really an issue until the application actually uses it. For example, on Linux the OS by default sets asides 8MB as stack memory for the main process thread as well as each subsequent thread created by the application. Thus if you have 10 additional threads, then that is 88MB virtual memory set aside. Note that this doesn't mean your RSS will be that value as it will only allocate real memory for that if actually required. Problem is that some VPS systems appear to work out your actual memory limit based on what is the theoretical amount that a process could use, which means the amount of virtual memory set aside for stacks is an issue as the virtual memory will be counted towards your memory limit in some way. Have seen this come up a few times lately where Apache was used to host web applications and worker MPM especially was used. Since Apache would by default create two child process each with 25 threads, the virtual memory usage can be quite high. Because of this, these people were finding very quickly that Apache would die through reaching their memory limit even though the real amount of memory it was using hadn't reached the limit. So, be careful not to get a VPS with too small a memory limit if you want to use Apache with lots of threads and/or processes. Same may apply for other applications as well to various degrees. Since 8MB for stack size for additional threads is probably a lot more than required, non Linux systems often use only 512KB (MacOS X), you can also use configuration to override the excessive default of Linux. For some background on this general problem and configuring Apache in particular to avoid problems see links in: http://groups.google.com/group/modwsgi/browse_frm/thread/5ace4e1c77214b43 Anyway, this is one oddity I have been paying attention to lately and you have given me a great opportunity for brain dumping my understanding of it so far. I may not truly understand it yet as don't have access to VPS systems to play with, but getting there. Even so, above may not be totally accurate picture just yet. :-) Graham --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web.py" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/webpy?hl=en -~----------~----~----~----~------~----~------~--~---
