From 3cbd31b5f6ba17e7590b814473fe1d5bb03ac86c Mon Sep 17 00:00:00 2001
From: Efimov Vasily <real@ispras.ru>
Date: Wed, 15 Jan 2020 17:27:54 +0300
Subject: [PATCH 1/3] CoDispatcher: do not print task profiling during normal
 operation

Signed-off-by: Efimov Vasily <real@ispras.ru>
---
 common/co_dispatcher.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/common/co_dispatcher.py b/common/co_dispatcher.py
index 79379aeb9..1ce461315 100644
--- a/common/co_dispatcher.py
+++ b/common/co_dispatcher.py
@@ -28,6 +28,12 @@
 from six import (
     StringIO
 )
+from .os_wrappers import (
+    ee
+)
+
+
+PROFILE_COTASK = ee("QDT_PROFILE_COTASK")
 
 
 class FailedCallee(RuntimeError):
@@ -215,7 +221,7 @@ def poll(self):
                     ready = True
 
             ti = t1 - t0
-            if ti > 0.05:
+            if PROFILE_COTASK and ti > 0.05:
                 sys.stderr.write("Task %s consumed %f sec during iteration "
                     # file:line is the line reference format supported by
                     # Eclipse IDE Console.

From ef3551687a313d37315ba3cf148938bf31e4150f Mon Sep 17 00:00:00 2001
From: Efimov Vasily <real@ispras.ru>
Date: Wed, 15 Jan 2020 17:28:15 +0300
Subject: [PATCH 2/3] TkCoDispatcher: do not print task profiling during normal
 operation

Signed-off-by: Efimov Vasily <real@ispras.ru>
---
 widgets/tk_co_dispatcher.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/widgets/tk_co_dispatcher.py b/widgets/tk_co_dispatcher.py
index ce4d2d11b..0f2d3fc0a 100644
--- a/widgets/tk_co_dispatcher.py
+++ b/widgets/tk_co_dispatcher.py
@@ -3,6 +3,7 @@
 ]
 
 from common import (
+    ee,
     CoDispatcher
 )
 from time import (
@@ -10,6 +11,10 @@
 )
 import sys
 
+
+PROFILE_COTASK = ee("QDT_PROFILE_COTASK")
+
+
 class TkCoDispatcher(CoDispatcher):
     """
     The coroutine task dispatcher uses Tk.after method to spread task work
@@ -31,7 +36,7 @@ def iteration(self):
         t0 = time()
         ready = CoDispatcher.iteration(self)
         ti = time() - t0
-        if ti > 0.1:
+        if PROFILE_COTASK and ti > 0.1:
 
             sys.stderr.write(("Iteration consumed %f sec\n" % ti)
                 + "Active tasks:\n  "

From 993815f18d62fa7333bf1c63944d6a21d2c73b09 Mon Sep 17 00:00:00 2001
From: Efimov Vasily <real@ispras.ru>
Date: Wed, 15 Jan 2020 17:39:35 +0300
Subject: [PATCH 3/3] README: add note about `QDT_PROFILE_COTASK`

Signed-off-by: Efimov Vasily <real@ispras.ru>
---
 README.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/README.md b/README.md
index 9576bdf4a..bf6d42383 100644
--- a/README.md
+++ b/README.md
@@ -793,3 +793,15 @@ For example:
 
 PYTHONPATH=".." python canvas_frame_test.py
 ```
+
+## Development tips
+
+### Environment variables
+
+Environment variables affect operation of QDT modules and tools.
+Commonly, a value is an `eval`uated Python expression which must return
+a boolean.
+
+* `QDT_PROFILE_COTASK`: turns on messages about coroutine-like tasks
+    that consumed too many time between `yield`s.
+* `grep` for `ee(` for other.