How many programes can run at a time on a single operating system?

Answer 1

There are a number of factors in play that all contribute to the maximum number of applications that can run at once, including RAM, swap, handles, committed memory, threads, and processes. A typical system with 4GB of RAM and 4GB of swap may be able to run approximately 150-300 smaller programs, such as Web Browsers, simple text editors, etc. Larger programs will reduce this estimate.

The largest server configuration of Windows, assuming the hardware existed to support it, would allow up to 8 million small programs to run, or more usefully, about 250,000-500,000 "typical" sized programs.

At some point, the number of CPUs and/or cores may also come into play, as running many programs at once will slow down the CPU. This maximum is far more noticeable on systems with tons of RAM and a slower processor. Assuming the programs are (mostly) idle, the estimates above would work, but during peak usage, the system would slow to a crawl.

Each processor or core can comfortably run a program at normal speed around 5% assuming light CPU usage. This would place the limit around 20 programs per core or processor installed; 8 cores would be around 160 total programs.

The maximum number of applications that can be run will depend on CPU responsiveness, total RAM used, and many other factors. This number may range from 1 large program to dozens, hundreds, or thousands of small programs. The only way a user can find out what the limits are of their system is to open as much as they can until the system won't let them; that is their maximum number.

There's hardly anyone that knows the internal limits of Windows, but the limits are high enough that it doesn't really matter, since RAM, CPU usage, and disk capacity would prevent any system from reaching the theoretical internal limits of the Windows Kernel.