[Rd] Managing DLLs with the same names in an R session

Patrick Aboyoun paboyoun at fhcrc.org
Fri Apr 24 20:07:43 CEST 2009

Thanks Brian. I'll stop trying to hack the code to work and opt for the 
dll rename option.


Prof Brian Ripley wrote:
> On Fri, 24 Apr 2009, Patrick Aboyoun wrote:
>> I am having a problem using two DLLs with the same name, but 
>> obviously located in different directories, in an R session. The 
>> troublesome package is the (Bioconductor) Rgraphviz package. It 
>> relies on (3rd party software) graphviz and imports functions from 
>> (Bioconductor) package graph. Unfortunately, the current stable 
>> release of graphviz for Windows
>> http://www.graphviz.org/pub/graphviz/stable/windows/graphviz-2.22.2.msi
>> contains a graph.dll in its bin directory. The situation is that 
>> Rgraphviz needs to link to the graph.dll from graphviz,
>> E:\paboyoun>..\biocbld\bbs-2.4-bioc\R\bin\R CMD build Rgraphviz
>> [...omitting output...]
>> ** libs
>> making DLL ...
>> [...omitting output...]
>> gcc -shared -s -o Rgraphviz.dll tmp.def LL_funcs.o Rgraphviz.o 
>> RgraphvizInit.o agopen.o agread.o agwr
>> ite.o bezier.o buildEdgeList.o buildNodeList.o doLayout.o 
>> graphvizVersion.o init.o -LC:/Graphviz2.22/
>> bin -lgvc -lgraph -lcdt -Le:/biocbld/bbs-2.4-bioc/R/bin -lR
>> [...omitting output...]
>> but at run time R dispatches to the graph.dll from the graph package 
>> to resolve the symbols.
>> R-2.9> Sys.which("graph.dll")
>>                       graph.dll
>> "C:\\GRAPHV~1.22\\bin\\graph.dll"
>> R-2.9> library(Rgraphviz)
>> Loading required package: graph
>> Loading required package: grid
>> << Message box appears:  The procedure entry point agclose could not 
>> be located in the dynamic link library graph.dll >>
>> Running Rterm.exe through the DependencyWalker software, I see that 
>> the gvc.dll and cdt.dll graphviz libraries are properly loaded, but 
>> the graph.dll dependency of Rgraphviz.dll links to the graph.dll 
>> library from the graph package. I tried passing the DLLpath for 
>> graphviz to the library.dynam function call when loading 
>> Rgraphviz.dll in the .onLoad function within Rgraphviz and it had no 
>> effect. I also tried library.dynam.unload/dyn.unload-ing the 
>> graph.dll from the graph package and then loading the Rgraphviz.dll 
>> followed by the reloading of the graph.dll from the graph package and 
>> the graph.dll dependencies become broken to the point that a call out 
>> to a graph.dll results in a GPF.
>> Is is possible to manage DLLs with the same name from R or do I need 
>> to rename one of the DLL names to make them unique?
> On Windows, the latter is the only completely reliable solution that 
> we know of.  We've been here with iconv.dll, and had to rename the R 
> copy to Riconv.dll as a result.  (Unfortunately, it depends on the 
> version of Windows and even the service pack installed. AFAICS some 
> versions of Windows only allow one DLL of a given name to be loaded by 
> a single process, here the R process.)
> There are (older?) Unix-alike OSes with similar issues.

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