From 71bd8b10edc6e29ca6d8c5262f91db64ad22a7c8 Mon Sep 17 00:00:00 2001
From: Javi Merino <javi.merino@arm.com>
Date: Tue, 30 Jul 2019 14:43:58 +0100
Subject: [PATCH] trace/systrace: make start() return when tracing has started
In SystraceCollector, start() returns after executing
subprocess.Popen() for systrace. That doesn't mean that systrace is
running though, the function can return even before systrace has had a
chance to execute anything. Therefore, when you run the command
you want to trace, systrace will miss the first seconds of the
execution.
Run systrace with -u to unbuffer its stdin and wait for it to print
"Starting tracing (stop with enter)" before returning.
Fixes #403
---
devlib/trace/systrace.py | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/devlib/trace/systrace.py b/devlib/trace/systrace.py
index c8f5285..a359360 100644
--- a/devlib/trace/systrace.py
+++ b/devlib/trace/systrace.py
@@ -107,7 +107,7 @@ class SystraceCollector(TraceCollector):
self._tmpfile = NamedTemporaryFile()
# pylint: disable=attribute-defined-outside-init
- self.systrace_cmd = '{} -o {} -e {}'.format(
+ self.systrace_cmd = 'python2 -u {} -o {} -e {}'.format(
self.systrace_binary,
self._tmpfile.name,
self.target.adb_name
@@ -137,9 +137,11 @@ class SystraceCollector(TraceCollector):
self._systrace_process = subprocess.Popen(
self.systrace_cmd,
stdin=subprocess.PIPE,
+ stdout=subprocess.PIPE,
shell=True,
universal_newlines=True
)
+ self._systrace_process.stdout.read(1)
def stop(self):
if not self._systrace_process: