|Windows Help > Windows Processes > dllhost.exe|
dllhost.exe - DLL Host ManagerWindows uses many processes to manage various aspects of internal OS activities. The dllhost.exe process is one of these; it's the DCOM DLL Host process and it's responsible for managing DLL (Dynamic Link Library) based applications. This process should never be disabled, as it may cause unstable performance, application failure, or even a system crash.
Microsoft's MSDN site states that the process is the "default DLL surrogate that can act as a host for your in-process components. The file Dllhost.exe is an executable component that you can run remotely and instruct to load any in-process component, providing the component with a surrogate parent process and security context."
DLL is Microsoft's implementation of the "shared library" methodology, which is also used in UNIX. It allows applications to use common external libraries rather than embedding library functions into individual binary files. This saves memory, makes library management easier, and allows multiple applications to make use of the same code.
The dllhost.exe process may appear more than once on a running Windows machine. The presence of multiple instances of the same thing (similar to svchost.exe) does not necessarily denote the presence of a virus or other malware.
As with many other built-in Windows components, the legitimate copy of this file lives in c:\windows\system32. If you find copies of this file elsewhere on your system, it may signal the presence of malware. Many malware authors make use of legitimate file names in an attempt to conceal their applications from users. If in doubt, be sure to download and run a current copy of SpySweeper, Spyware Search and Destroy, or another malware scanner.
It's possible for a badly written application to cause a running instance of dllhost.exe to consume a large percentage of system resources (memory, CPU, etc.). Some users believe this means the application is infected or transmitting data to a remote site, but this may not be the case. Poorly written programs, bugs, and incompatibilities between an application and DLL can also trigger resource hogging. Stopping the misbehaving application should cause the dllhost.exe instance to either exit or drop to an insignificant level of resource usage.