tests: add utility to easily profile node performance with perf

Introduces `TestNode.profile_with_perf()` context manager which
samples node execution to produce profiling data.

Also introduces a test framework flag, `--perf`, which will run
perf on all nodes for the duration of a given test.

1 files changed, 14 insertions, 2 deletions

diff --git a/test/functional/test_framework/test_framework.py b/test/functional/test_framework/test_framework.py
index 352fa32b5b..240d9ce87c 100755
--- a/test/functional/test_framework/test_framework.py
+++ b/test/functional/test_framework/test_framework.py
@@ -128,6 +128,8 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                             help="Attach a python debugger if test fails")
         parser.add_argument("--usecli", dest="usecli", default=False, action="store_true",
                             help="use bitcoin-cli instead of RPC for all commands")
+        parser.add_argument("--perf", dest="perf", default=False, action="store_true",
+                            help="profile running nodes with perf for the duration of the test")
         self.add_options(parser)
         self.options = parser.parse_args()
 
@@ -201,11 +203,20 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                 node.cleanup_on_exit = False
             self.log.info("Note: bitcoinds were not stopped and may still be running")
 
-        if not self.options.nocleanup and not self.options.noshutdown and success != TestStatus.FAILED:
+        should_clean_up = (
+            not self.options.nocleanup and
+            not self.options.noshutdown and
+            success != TestStatus.FAILED and
+            not self.options.perf
+        )
+        if should_clean_up:
             self.log.info("Cleaning up {} on exit".format(self.options.tmpdir))
             cleanup_tree_on_exit = True
+        elif self.options.perf:
+            self.log.warning("Not cleaning up dir {} due to perf data".format(self.options.tmpdir))
+            cleanup_tree_on_exit = False
         else:
-            self.log.warning("Not cleaning up dir %s" % self.options.tmpdir)
+            self.log.warning("Not cleaning up dir {}".format(self.options.tmpdir))
             cleanup_tree_on_exit = False
 
         if success == TestStatus.PASSED:
@@ -309,6 +320,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                 extra_conf=extra_confs[i],
                 extra_args=extra_args[i],
                 use_cli=self.options.usecli,
+                start_perf=self.options.perf,
             ))
 
     def start_node(self, i, *args, **kwargs):