Require Python 3.9 for PerfkitBenchmarker

This will allow using newer language features.

PiperOrigin-RevId: 465148664

CHANGES.next.md

@@ -1,5 +1,6 @@
 ### Breaking changes:
 
+-   Require Python 3.9+
 -   The core_os os_type was removed from the Azure provider as
     [the image was deleted](https://docs.microsoft.com/en-us/azure/virtual-machines/linux/endorsed-distros#supported-distributions-and-versions),
     -   It will be replaced by

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.7
+FROM python:3.9
 
 WORKDIR /pkb
 

README.md

@@ -130,8 +130,8 @@ running with PKB.
 ## Python 3
 
 The recommended way to install and run PKB is in a virtualenv with the latest
-version of Python 3. Most Linux distributions and recent Mac OS X versions
-already have Python 3 installed at `/usr/bin/python3`.
+version of Python 3 (at least Python 3.9). Most Linux distributions and recent
+Mac OS X versions already have Python 3 installed at `/usr/bin/python3`.
 
 If Python is not installed, you can likely install it using your distribution's
 package manager, or see the

docs/getting-started.md

@@ -5,8 +5,8 @@ layout: page
 
 ## Python
 
-PerfKitBenchmarker requires [Python](https://www.python.org/downloads/) and is
-tested on Python 3.7. We recommend using a
+PerfKitBenchmarker requires [Python](https://www.python.org/downloads/) 3.9+
+and is tested on Python 3.9. We recommend using a
 [virtual environment](https://docs.python.org/3/tutorial/venv.html) to manage
 different Python versions and their required `pip` dependencies.
 

perfkitbenchmarker/pkb.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""Runs all benchmarks in PerfKitBenchmarker.
+"""Runs benchmarks in PerfKitBenchmarker.
 
 All benchmarks in PerfKitBenchmarker export the following interface:
 
@@ -1792,6 +1792,8 @@ def CollectMeminfo(vm):
 
 
 def Main():
+  """Entrypoint for PerfKitBenchmarker."""
+  assert sys.version_info >= (3, 9), 'PerfKitBenchmarker requires Python 3.9+'
   log_util.ConfigureBasicLogging()
   _InjectBenchmarkInfoIntoDocumentation()
   _ParseFlags()

requirements.txt

@@ -20,7 +20,8 @@ blinker>=1.3
 packaging
 pandas>=1.1.5
 PyYAML==5.4.1
-pint>=0.7
+# TODO(pclay): fix % parsing in 0.19+
+pint<0.19
 numpy>=1.16.5
 contextlib2>=0.5.1
 six>=1.13.0
@@ -30,3 +31,7 @@ google-cloud-datastore
 google-cloud-monitoring
 beautifulsoup4
 requests
+
+# unlike setup.py requirements.txt cannot require a Python version AFAICT
+# this hack requires a non-existent package when Python is less than 3.9
+PerfkitBenchmarker_requires_Python_39;python_version<"3.9"

tox.ini

@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py37,flake8,scripts
+envlist = py39,py310,flake8,scripts
 
 [testenv]
 usedevelop = True