flush stdio after each execution

Author: Christopher Doris

Diff for: pysrc/juliacall/ipython.py

@@ -22,8 +22,7 @@ class JuliaMagics(Magics):
     def julia(self, line, cell=None):
         code = line if cell is None else cell
         ans = Main.seval('begin\n' + code + '\nend')
-        Base.flush(Base.stdout)
-        Base.flush(Base.stderr)
+        PythonCall._flush_stdio()
         if not code.strip().endswith(';'):
             return ans
 
@@ -35,10 +34,21 @@ def load_ipython_extension(ip):
     PythonCall.seval("""begin
         const _redirected_stdout = redirect_stdout()
         const _redirected_stderr = redirect_stderr()
-        const _py_stdout = PyIO(pyimport("sys" => "stdout"), buflen=1)
-        const _py_stderr = PyIO(pyimport("sys" => "stderr"), buflen=1)
+        const _py_stdout = PyIO(pyimport("sys" => "stdout"))
+        const _py_stderr = PyIO(pyimport("sys" => "stderr"))
         const _redirect_stdout_task = @async write($_py_stdout, $_redirected_stdout)
         const _redirect_stderr_task = @async write($_py_stderr, $_redirected_stderr)
+        function _flush_stdio()
+            flush(stderr)
+            flush(stdout)
+            flush(_redirected_stderr)
+            flush(_redirected_stdout)
+            flush(_py_stderr)
+            flush(_py_stdout)
+            nothing
+        end
         pushdisplay(PythonDisplay())
         pushdisplay(IPythonDisplay())
+        nothing
     end""")
+    ip.events.register('post_execute', PythonCall._flush_stdio)