Caution! Can result in severe system slowdown or even crash the operating system. Don't click on the button below unless you know what you are doing.
Suggested Usage - Software Developer
Test application behaviour under low memory conditions. Simulate long-term memory leak conditions.
Are any error messages generated - to the end user, to the system administrator?
Does the application start behaving strangely, or die silently and mysteriously?
Is there any data corruption?
Suggested Usage - System Administrator
Test system recovery procedures before going live.
Is the low memory condition picked up by any remote monitoring software and
an alert issued?
Can you recover control of the system and start killing processes, or do
you need to do a hard reset?
Does remote access work or do you need a local terminal for reliable access?
Are there sufficient system logs to identify the application that caused
the low memory condition, and the time of occurrence?
Consider deploying a periodic process to automatically reboot if a severe
low memory condition is detected. If one is already deployed, did it work?
Test accuracy of OS system tools - is the reported free memory correct (see
example below), especially inside a virtual machine?
Suggested Usage - Power User
Test available memory, even in locked down systems, where access to system
tools is blocked (see example below).
Example
Output below is for a lightly loaded 256 MB RAM system, showing that about
130 MB is free for application use.
*** Start ***
Speed at (10 megabytes): 237.52 **************************
Speed at (20 megabytes): 212.76 ***********************
Speed at (30 megabytes): 269.54 *****************************
Speed at (40 megabytes): 370.37 ***************************************
Speed at (50 megabytes): 398.4 ******************************************
Speed at (60 megabytes): 400 *******************************************
Speed at (70 megabytes): 370.37 ***************************************
Speed at (80 megabytes): 398.4 ******************************************
Speed at (90 megabytes): 416.66 ********************************************
Speed at (100 megabytes): 383.14 *****************************************
Speed at (110 megabytes): 384.61 *****************************************
Speed at (120 megabytes): 370.37 ***************************************
Speed at (130 megabytes): 343.64 *************************************
Speed at (140 megabytes): 96.06 ***********
Speed at (150 megabytes): 27.65 ***
Speed at (160 megabytes): 53.41 ******
Speed at (170 megabytes): 13.65 **
Speed at (180 megabytes): 149.03 ****************
Speed at (190 megabytes): 72.35 ********
Speed at (200 megabytes): 151.28 ****************
However, when the system is loaded by another application, the result becomes
less regular. Note how the highest allocation speed is much lower compared
to the example above.
*** Start ***
Speed at (10 megabytes): 118.76 **************************
Speed at (20 megabytes): 78.61 *****************
Speed at (30 megabytes): 97.84 *********************
Speed at (40 megabytes): 107.41 ***********************
Speed at (50 megabytes): 110.98 ************************
Speed at (60 megabytes): 66.97 ***************
Speed at (70 megabytes): 98.91 *********************
Speed at (80 megabytes): 83.89 ******************
Speed at (90 megabytes): 82.5 ******************
Speed at (100 megabytes): 126.42 ***************************
Speed at (110 megabytes): 114.81 *************************
Speed at (120 megabytes): 99.8 **********************
Speed at (130 megabytes): 96.99 *********************
Speed at (140 megabytes): 21.51 *****
Speed at (150 megabytes): 29.89 *******
Speed at (160 megabytes): 68.39 ***************
Speed at (170 megabytes): 56.08 ************
Speed at (180 megabytes): 83.89 ******************
Speed at (190 megabytes): 86.88 *******************
Speed at (200 megabytes): 100.9 **********************
Details
Works by allocating random string to JavaScript array. Program assumes 2
bytes for each character - true for IE and Firefox under Windows XP (likely
due to Unicode). To confirm if this is true for your system, check the web
browser's virtual memory size when the program runs and see if it corresponds
to the displayed value in the blue box.
Results are approximate only. Browser overhead, array storage overhead, are
not considered.
Memory is released at the end of the test, by zeroing out the JavaScript
array. This doesn't release the memory in some browsers. Best to close the
browser to free up the memory, after running the test.
Allocation speed displayed is for comparison only. It has no absolute meaning.
Maximum memory allocated is limited to 1.7 GB. Above this, IE and Firefox
(on Windows XP) choke and hang.
Use at your own risk
These online tools are meant to be used by IT professionals and power users.
People who
know what they are doing and who understand the limitations of web-based
software
recognize the possibility of bugs in software, the complexity of the interactions
between applications, CPUs (including multi-core), RAM, operating system
(task scheduler, memory manager etc). And therefore carefully interpret and
check the results reported by any software.
Contact
Send compliments, suggestions, complaints to:
Copyright
This page and the JavaScript code in it, is copyright (c) 2007 by Yuen Kit
Mun, all rights reserved.
To support the development of this and other free software ("Free as in beer"),
please don't copy the code or place the HTML file on an Internet web server
(intranet or localhost web server is okay, don't remove this copyright notice).
But do tell others about this URL.
