thread safety fix in compiling regexes (#32544)

Author: JeffBezanson

base/pcre.jl

@@ -25,6 +25,8 @@ end
 
 const THREAD_MATCH_CONTEXTS = Ptr{Cvoid}[C_NULL]
 
+PCRE_COMPILE_LOCK = nothing
+
 _tid() = Int(ccall(:jl_threadid, Int16, ())+1)
 _nth() = Int(unsafe_load(cglobal(:jl_n_threads, Cint)))
 
@@ -40,6 +42,7 @@ end
 function __init__()
     resize!(THREAD_MATCH_CONTEXTS, _nth())
     fill!(THREAD_MATCH_CONTEXTS, C_NULL)
+    global PCRE_COMPILE_LOCK = Threads.SpinLock()
 end
 
 # supported options for different use cases

base/regex.jl

@@ -61,8 +61,21 @@ Regex(pattern::AbstractString) = Regex(pattern, DEFAULT_COMPILER_OPTS, DEFAULT_M
 
 function compile(regex::Regex)
     if regex.regex == C_NULL
-        regex.regex = PCRE.compile(regex.pattern, regex.compile_options)
-        PCRE.jit_compile(regex.regex)
+        if PCRE.PCRE_COMPILE_LOCK === nothing
+            regex.regex = PCRE.compile(regex.pattern, regex.compile_options)
+            PCRE.jit_compile(regex.regex)
+        else
+            l = PCRE.PCRE_COMPILE_LOCK::Threads.SpinLock
+            lock(l)
+            try
+                if regex.regex == C_NULL
+                    regex.regex = PCRE.compile(regex.pattern, regex.compile_options)
+                    PCRE.jit_compile(regex.regex)
+                end
+            finally
+                unlock(l)
+            end
+        end
     end
     regex
 end