LoadRunner Upload – Download file / Operative System 4 GB Memory Limitation

Each operating system has a physical memory limit which reciprocally define the boundaries for memory and address space that can be used by the processes, services, objects and services executed over the current operative system version.

Following is the memory limits that are present in Windows OS and how it affects the mdrv.exe process emulation when uploading/downloading large files, generating a reaction where the mdrv will crash, hangs or result in a memory violation.

 The implementation of LR file uploading/downloading is not optimized for huge file. It always reads all the files to memory before upload. That means, for files with 1 GB in size, mdrv has to   obtain 1 GB sequential memory space in the process for each Vuser. However, mdrv is a 32 bit process. In windows system, a 32 bit process has at most 4 GB in memory space, and only 2 GB of them can be used by developer. If the user tries to upload a file with 2 GB in size, it is almost impossible to find proper memory for it, since the other functions will also use some memory.

When the file size is smaller, like 500 MB to 1 GB, it will be possible to make the upload successful. But when we run the script in controller, we should make the Vuser run in process mode.

From the Operating System perspective and as a workaround it is possible to switch the memory use and memory address space allocation to 3 GB for the application and less 1 GB for the operating system.

In order to increase the memory and address space to 3 GB limit we need to be implement the following steps.

  1. Right-click on the Command Prompt icon in the Accessories program group of the Start menu. Click Run as Administrator.
  2. At the command prompt, enter:

bcdedit /set IncreaseUserVa 3072

  1. Restart the computer.
  2. Run the script one more time in VuGen and in the Controller using the LG as process.

For disabling  the  memory increase here is the command.

  1. Right-click on the Command Prompt icon in the Accessories program group of the Start menu. Click Run as Administrator.
  2. At the command prompt, enter:

bcdedit /deletevalue IncreaseUserVa

  1. Restart the computer.
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