test_get_map fails on 1-core VM

[bmwiedemann]

Context

While working on on reproducible builds for openSUSE, I found that our python-MapProxy would not build in 1-core VMs because tests fail.

Expected Behavior

Tests should pass

Actual Behavior

 =================================== FAILURES ===================================
 ___________________________ TestWMS110.test_get_map ____________________________
 
 self = <mapproxy.test.system.test_wms.TestWMS110 object at 0x7fea4097c0d0>
 app = <mapproxy.test.system.WSGITestApp object at 0x7fea33fb33a0>
 cache_dir = local('/tmp/pytest-of-abuild/pytest-0/base_dir50/cache_data')
 
     def test_get_map(self, app, cache_dir):
         with tmp_image((256, 256), format="jpeg") as img: 
             expected_req = (
                 {
                     "path": r"/service?LAYERs=foo,bar&SERVICE=WMS&FORMAT=image%2Fjpeg"
                     "&REQUEST=GetMap&HEIGHT=256&SRS=EPSG%3A900913&styles="
                     "&VERSION=1.1.1&BBOX=0.0,0.0,20037508.3428,20037508.3428"
                     "&WIDTH=256"
                 },
                 {"body": img.read(), "headers": {"content-type": "image/jpeg"}},
             )
             with mock_httpd(
                 ("localhost", 42423), [expected_req], bbox_aware_query_comparator=True
             ):
                 self.common_map_req.params["bbox"] = "0,0,180,90"
                 resp = app.get(self.common_map_req)
 >               assert 35000 < int(resp.headers["Content-length"]) < 75000 
 E               AssertionError: assert 35000 < 594
 E                +  where 594 = int('594')
 
 mapproxy/test/system/test_wms.py:1003: AssertionError
 ----------------------------- Captured stdout call -----------------------------
 requests mismatch:
  -  requests mismatch (requests differ), expected:
         /service?LAYERs=foo,bar&SERVICE=WMS&FORMAT=image%2Fjpeg&REQUEST=GetMap&HEIGHT=256&SRS=EPSG%3A900913&styles=&VERSION=1.1.1&BBOX=0.0,0.0,20037508.3428,20037508.3428&WIDTH=256
       got:
         /service?layers=foo,bar&format=image%2Fjpeg&bbox=0.0,0.0,10018754.171394622,10018754.171394622&width=256&height=256&srs=EPSG%3A900913&request=GetMap&version=1.1.1&service=WMS&styles=
  -  requests mismatch (requests params differ), expected:
         {('bbox', '0.0,0.0,20037508.3428,20037508.3428')}
       got:
         {('bbox', '0.0,0.0,10018754.171394622,10018754.171394622')}
 ------------------------------ Captured log call -------------------------------
 WARNING  mapproxy.source.wms:wms.py:100 could not retrieve WMS map: Internal HTTP error "http://localhost:42423/service?layers=foo,bar&format=image%2Fjpeg&bbox=0.0,0.0,20037508.342789244,20037508.342789244&width=256&height=256&srs=EPSG%3A900913&request=GetMap&version=1.1.1&service=WMS&styles=": ConnectionResetError(104, 'Connection reset by peer')
[...]
 FAILED mapproxy/test/system/test_wms.py::TestWMS110::test_get_map - Assertion...
 FAILED mapproxy/test/system/test_wms.py::TestWMS100::test_get_map - Assertion...
 FAILED mapproxy/test/system/test_wms.py::TestWMS130::test_get_map - Assertion...
 ==== 3 failed, 1617 passed, 38 skipped, 41 deselected, 8 warnings in 31.08s ====

Possible Fix

Steps to Reproduce

1. have a Debian or openSUSE Linux with osc + obs-build installed
2. osc co openSUSE:Factory/python-MapProxy && cd $_
3. osc build --vm-type=kvm -j1 --noservice --clean standard

Maybe can also be trigged by running tests as taskset 1 pytest

Context

Your Environment

• Version used: MapProxy-1.13.0
• Environment name and version: python 3.8.10
• Operating System and version: openSUSE Tumbleweed 20210610 ; no Internet during build+test