fix #177: avoid GIL deadlock

fract4d · Oct 29, 2020 · 3e3893b · 3e3893b
1 parent e94cbce
commit 3e3893b
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Showing 3 changed files with 25 additions and 15 deletions.
diff --git a/fract4d/c/fract4dc/calcargs.cpp b/fract4d/c/fract4dc/calcargs.cpp
@@ -1,5 +1,4 @@
 #include "Python.h"
-#include <mutex>
 
 #include "calcargs.h"
 
@@ -18,36 +17,30 @@ calc_args::calc_args()
     params = new double[N_PARAMS];
 }
 
-static std::mutex ref_count_mutex;
-
 void calc_args::set_cmap(PyObject *pycmap_)
 {
     pycmap = pycmap_;
     cmap = colormaps::cmap_fromcapsule(pycmap);
-    const std::lock_guard<std::mutex> lock(ref_count_mutex);
     Py_XINCREF(pycmap);
 }
 
 void calc_args::set_pfo(PyObject *pypfo_)
 {
     pypfo = pypfo_;
     pfo = (loaders::pf_fromcapsule(pypfo))->pfo;
-    const std::lock_guard<std::mutex> lock(ref_count_mutex);
     Py_XINCREF(pypfo);
 }
 
 void calc_args::set_im(PyObject *pyim_)
 {
     pyim = pyim_;
     im = images::image_fromcapsule(pyim);
-    const std::lock_guard<std::mutex> lock(ref_count_mutex);
     Py_XINCREF(pyim);
 }
 void calc_args::set_site(PyObject *pysite_)
 {
     pysite = pysite_;
     site = sites::site_fromcapsule(pysite);
-    const std::lock_guard<std::mutex> lock(ref_count_mutex);
     Py_XINCREF(pysite);
 }
 
@@ -57,7 +50,6 @@ calc_args::~calc_args()
 #ifdef DEBUG_CREATION
     fprintf(stderr, "%p : CA : DTOR\n", this);
 #endif
-    const std::lock_guard<std::mutex> lock(ref_count_mutex);
     Py_XDECREF(pycmap);
     Py_XDECREF(pypfo);
     Py_XDECREF(pyim);

diff --git a/fract4d/c/fract4dc/calcs.cpp b/fract4d/c/fract4dc/calcs.cpp
@@ -46,11 +46,14 @@ namespace calcs {
 
         if (cargs->asynchronous)
         {
-            auto &site = *cargs->site;
-            site.interrupt();
-            site.wait();
-            site.start();
-            site.set_thread(std::thread(calculation_thread, cargs));
+            std::thread t([cargs](){
+                auto &site = *cargs->site;
+                site.interrupt();
+                site.wait();
+                site.start();
+                site.set_thread(std::thread(calculation_thread, cargs));
+            });
+            t.detach();
         }
         else
         {
@@ -76,6 +79,21 @@ namespace calcs {
     }
 }
 
+struct GIL_guard {
+    PyGILState_STATE state;
+    bool active;
+    GIL_guard():
+        state(PyGILState_Ensure()), active(true) {}
+    void restore()
+    {
+        PyGILState_Release(state);
+        active = false;
+    }
+    ~GIL_guard()
+    {
+        if (active) restore();
+    }
+};
 
 void * calculation_thread(calc_args *args)
 {
@@ -94,9 +112,8 @@ void * calculation_thread(calc_args *args)
 #ifdef DEBUG_THREADS
     std::cerr << args << " : CA : ENDCALC(" << std::this_thread::get_id() << ")\n";
 #endif
-    PyGILState_STATE gstate = PyGILState_Ensure();
+    GIL_guard e;
     delete args;
-    PyGILState_Release(gstate);
     return NULL;
 }
 

diff --git a/fract4d/c/fract4dmodule.cpp b/fract4d/c/fract4dmodule.cpp
@@ -651,6 +651,7 @@ PyInit_fract4dc(void)
         return NULL;
     }
 
+    // todo: check this https://docs.python.org/3/c-api/init.html#c.PyEval_InitThreads
     PyEval_InitThreads();
 
     /* expose some constants */