Today (Saturday) We will make some minor tuning adjustments to MySQL.

You may experience 2 up to 10 seconds "glitch time" when we restart MySQL. We expect to make these adjustments around 1AM Eastern Daylight Saving Time (EDT) US.

How to deal with lots of data in memory in order not to run out of memory

Login or Register to Reply

Thread Tools Search this Thread
# 1  
How to deal with lots of data in memory in order not to run out of memory


I'm trying to learn how to manage memory when I have to deal with lots of data.

Basically I'm indexing a huge file (5GB, but it can be bigger), by creating tables that
holds offset <-> startOfSomeData information. Currently I'm mapping the whole file at
once (yep!) but of course the application quickly run outs of memory and malloc'ing
a new table fails after a bit.

My first question, which is more a request for confirmation, is the following.
Does the mapped file counts in memory usage? I'd say yes at 99,9% but I'd like
to be sure.

Second I'd like to know what syscall are available in order to retrieve memory
information of the calling process (how much memory used, how much left etc..) ?

I'm of course going to map a few pages at the time, although it'll be more tricky
to parse the file. Anyway, I'd like to know how I should deal with the tables I create and
I keep in memory. If I dump a few tables to a temporary file, and mmap it for quick access, it'd be the same thing if the answer to my first question is yes. I definitely
would not want the kernel to start swapping memory, but I'd rather have a thread
that concurrently writes those table to a file, for later retrieve.

Anyhow, my main concern is not to run out of memory (i.e. malloc has not to fail).

Any kind of suggestions for people with more expertise are very welcomed.
I'm eager to learn.

# 2  
Yes memory mapping counts as part of your process. But it is possible to map a file shared, and have another process actually process the file. That does not solve the memory usage problem necessarily. If you are running out of memory see how ulimit is set.

ulimit example -
/home/jmcnama> ulimit -a
time(seconds)        unlimited
file(blocks)         unlimited
data(kbytes)         2015464
stack(kbytes)        256000
memory(kbytes)       unlimited
coredump(blocks)     4194303

The two red lines apply to your question.

getrusage() returns resource usage for a parent process and it's children.
setrusage allows you to change ulimit soft values - you cannot go beyond the hard limits unless the sysadmin reconfigures your account/kernel.

Also you can increase virtual memory simply by adding swap space. Virtual memory (if ulimit for memory == unlimited) is the actual limit for process memory space.

check out vmstat for more information.
Login or Register to Reply

Thread Tools Search this Thread
Search this Thread:
Advanced Search

10 More Discussions You Might Find Interesting

1. AIX

High Paging when lots of free memory AIX 5.3

I am new to AIX, I have few AIX 5.3 servers and I could see there are significant difference in paging space utilization on servers even though they are running same applications below server is working fine which shows 2-5 % paging usage throuh out the day cpu_scale_memp = 8... (12 Replies)
Discussion started by: bibish
12 Replies

2. Solaris

[DOUBT] Memory high in idle process on Solaris 10 (Memory Utilization > 90%)

Hi Experts, Our servers running Solaris 10 with SAP Application. The memory utilization always >90%, but the process on SAP is too less even nothing. Why memory utilization on solaris always looks high? I have statement about memory on solaris, is this true: Memory in solaris is used for... (4 Replies)
Discussion started by: edydsuranta
4 Replies

3. AIX

Lots of page faults and free memory

Hello, I've been reading your forums for quite a while and the great amount of information I find here always come in hand.This time however, I need some specific help... I have a doubt with an AIX server which I'm failing to understand as I'm new to its concept of memory management... ... (8 Replies)
Discussion started by: flpgdt
8 Replies

4. Solaris

restrcit physical memory with zone.max-locked-memory

Is it possible to restrict physical memory in solaris zone with zone.max-locked-memory just like we can do with rcapd ? I do not want to used rcapd (1 Reply)
Discussion started by: fugitive
1 Replies

5. Solaris

How to find Total and Free Physical Memory and Logical Memory in SOLARIS 9

Hi, Im working on Solaris 9 on SPARC-32 bit running on an Ultra-80, and I have to find out the following:- 1. Total Physical Memory in the system(total RAM). 2. Available Physical Memory(i.e. RAM Usage) 3. Total (Logical) Memory in the system 4. Available (Logical) Memory. I know... (4 Replies)
Discussion started by: 0ktalmagik
4 Replies

6. Programming

malloc gives the same memory to two different nodes. How to deal with it?

When allocating memory for two different nodes, the resulting memory are the same. Clearly, this will lead to a mistake. This happened in a function. And the process must be in a function. (gdb) p tree->list $43 = (node *) 0x8be4180 (gdb) p tree->list $44 = (node *) 0x8be4180 At the... (2 Replies)
Discussion started by: cdbug
2 Replies

7. AIX

ulimits max locked memory virtual memory

Hi, Would any one be so kind to explain me : are ulimits defined for each user seperately ? When ? Specialy what is the impact of : max locked memory and virtual memory on performance of applications for a user. Many thanks. PS : this is what I can see in MAN : ulimit ] ... (5 Replies)
Discussion started by: big123456
5 Replies

8. HP-UX

How can I get memory usage or anything that show memory used from sar file?

Refer from title: How can i get memory used or anything that can show memory from sar file example on solaris:- we can use sar with option to show memory used at time that sar crontab run. on HP-UX, it not has option to see memory used. But i think it may be have some parameter or some... (1 Reply)
Discussion started by: panithat
1 Replies

9. HP-UX

Order process by consumed memory

Hi! I am new to HP-UX. :o By using the command glance, I found the user memory usage was very high. I would like to know is there any command can show the process which consume most available memory ? (Just like the command top, but order by memory, not CPU) (1 Reply)
Discussion started by: alfredo
1 Replies

10. UNIX for Advanced & Expert Users

Shared memory shortage but lots of unused memory

I am running HP-UX B.11.11. I'm increasing a parameter for a database engine so that it uses more memory to buffer the disk drive (to speed up performance). I have over 5GB of memory not being used. But when I try to start the DB with the increased buffer parameter I get told. "Not... (1 Reply)
Discussion started by: cjcamaro
1 Replies

Featured Tech Videos