Add a warning against having multiple copies of a shared library loaded

base/Base.jl

@@ -250,15 +250,15 @@ include("missing.jl")
 # version
 include("version.jl")
 
+# Logging
+include("logging.jl")
+using .CoreLogging
+
 # system & environment
 include("sysinfo.jl")
 include("libc.jl")
 using .Libc: getpid, gethostname, time
 
-# Logging
-include("logging.jl")
-using .CoreLogging
-
 # Concurrency
 include("linked_list.jl")
 include("condition.jl")

base/libdl.jl

@@ -9,7 +9,7 @@ import Base.DL_LOAD_PATH
 
 export DL_LOAD_PATH, RTLD_DEEPBIND, RTLD_FIRST, RTLD_GLOBAL, RTLD_LAZY, RTLD_LOCAL,
     RTLD_NODELETE, RTLD_NOLOAD, RTLD_NOW, dlclose, dlopen, dlopen_e, dlsym, dlsym_e,
-    dlpath, find_library, dlext, dllist
+    dlpath, find_library, dlext, dllist, check_dllist
 
 """
     DL_LOAD_PATH
@@ -76,6 +76,57 @@ function dlsym_e(hnd::Ptr, s::Union{Symbol,AbstractString})
     return something(dlsym(hnd, s; throw_error=false), C_NULL)
 end
 
+if Sys.isapple()
+    const dlpattern = r"^([^.]+).*\.dylib$"
+elseif Sys.iswindows()
+    const dlpattern = r"^(.+)\.dll$"
+else
+    #assume Sys.islinux, or similar
+    const dlpattern = r"^(.+?)\.so(?:\..*)?$"
+end
+
+const _dlname_cache = Dict{String, SubString{String}}()
+
+"""
+    dlname(fullpath::String)
+
+Returns the name of the library.
+"""
+function dlname(fullpath::String)::SubString{String}
+    cache = get(_dlname_cache, fullpath, "")
+    cache != "" && return cache
+    bn = basename(fullpath)
+    m = match(dlpattern, bn)
+    ret = isnothing(m) ? bn : m.captures[1]
+    _dlname_cache[fullpath] = ret
+    return ret
+end
+
+"""
+    check_dllist()
+
+Check wheather the same shared library is loaded from two different files.
+The `warnings` determines if the warnings are printed to the console.
+"""
+function check_dllist()
+    fullpaths = dllist()
+    names = dlname.(fullpaths)
+    perm = sortperm(names)
+    dlabspath(x) = isfile(x) ? abspath(realpath(x)) : x
+    for i in 1:length(names)-1
+        p1, p2 = perm[i], perm[i+1]
+        if names[p1] == names[p2]
+            if dlabspath(fullpaths[p1]) == dlabspath(fullpaths[p2])
+                continue
+            end
+            @warn """Detected possible duplicate library loaded: $(names[p1])
+This may lead to unexpected behavior!
+$(fullpaths[p1])
+$(fullpaths[p2])""" maxlog=1
+        end
+    end
+end
+
 """
     dlopen(libfile::AbstractString [, flags::Integer]; throw_error:Bool = true)
 
@@ -113,11 +164,12 @@ function dlopen end
 dlopen(s::Symbol, flags::Integer = RTLD_LAZY | RTLD_DEEPBIND; kwargs...) =
     dlopen(string(s), flags; kwargs...)
 
-function dlopen(s::AbstractString, flags::Integer = RTLD_LAZY | RTLD_DEEPBIND; throw_error::Bool = true)
+function dlopen(s::AbstractString, flags::Integer = RTLD_LAZY | RTLD_DEEPBIND; throw_error::Bool = true, warnings::Bool = true)
     ret = ccall(:jl_load_dynamic_library, Ptr{Cvoid}, (Cstring,UInt32,Cint), s, flags, Cint(throw_error))
     if ret == C_NULL
         return nothing
     end
+    warnings && check_dllist()
     return ret
 end
 

stdlib/Libdl/src/Libdl.jl

@@ -4,10 +4,10 @@ module Libdl
 # Just re-export Base.Libc.Libdl:
 export DL_LOAD_PATH, RTLD_DEEPBIND, RTLD_FIRST, RTLD_GLOBAL, RTLD_LAZY, RTLD_LOCAL,
     RTLD_NODELETE, RTLD_NOLOAD, RTLD_NOW, dlclose, dlopen, dlopen_e, dlsym, dlsym_e,
-    dlpath, find_library, dlext, dllist
+    dlpath, find_library, dlext, dllist, check_dllist
 
 import Base.Libc.Libdl: DL_LOAD_PATH, RTLD_DEEPBIND, RTLD_FIRST, RTLD_GLOBAL, RTLD_LAZY, RTLD_LOCAL,
                         RTLD_NODELETE, RTLD_NOLOAD, RTLD_NOW, dlclose, dlopen, dlopen_e, dlsym, dlsym_e,
-                        dlpath, find_library, dlext, dllist
+                        dlpath, find_library, dlext, dllist, check_dllist
 
 end # module