(also dynamically loaded library (DLL), dynamically linked library)
Dynamic library definition
A concept in programming in which shared libraries containing special functions are initiated only during the course of a program’s execution. This minimizes the size of the overall program and paves the way for improved application performance while consuming less memory. In almost all software packages, specific functions can be separated into their own distinct modules, which enable loading on demand.
Benefits of dynamic libraries
- Fewer faults. Because the DLL is not constantly retrieved from the disk, runtime issues are less likely to arise. The same RAM can be shared by multiple processes at once, which eliminates the possibility of paging errors.
- Memory efficiency. DLLs improve the speed, memory use, and disk space utilization of operating systems and programs. Since the files aren’t loaded alongside the main program, memory is conserved.
- Modular architecture. DLL functions as a component of a modular architecture that enables the delivery of a program in distinct parts. It is not necessary for the developer to set up the entire program in one go. A few libraries and components can be swapped out for new ones without having to rewrite the whole code.
Limitations of dynamic libraries
- Errors. Certain executables need DLLs to run. If the DLL is missing, the application may fail to start and display an error message.
- Exploits. DLL hijacking, also called DLL injection, exploits the order in which the Windows operating system loads DLLs. Threat actors can introduce malicious .dll files where legitimate ones should load. The main application could then load the malicious DLL file.
- Speed. Compared to static linking, dynamic linking takes more time. Because dynamic linking occurs during runtime or load time, it consumes more CPU resources than loading during compile time.
Fixing dynamic library errors
- Troubleshooting the DLL file. Restart the computer and check the recycle bin for the file. Deleted files not in the recycle bin can be recovered with a file recovery application.
- Doing a malware scan. Doing a system restore from an earlier backup will return the computer’s OS to its former condition before the DLL file becomes corrupted.
- Using troubleshooting tools like Dependency Walker, DLL universal problem solver, and a DLL help database.