fix: only call signal if executing on the main thread (#10677)
fix: only call signal if executing on the main thread (#10677)


airbnb/caravel,mistercrunch/panoramix,zhouyao1994/incubator-superset,apache/incubator-superset,airbnb/caravel,apache/incubator-superset,airbnb/superset,zhouyao1994/incubator-superset,zhouyao1994/incubator-superset,mistercrunch/panoramix,mistercrunch/panoramix,airbnb/caravel,apache/incubator-superset,apache/incubator-superset,apache/incubator-superset,zhouyao1994/incubator-superset,airbnb/superset,airbnb/superset,airbnb/caravel,zhouyao1994/incubator-superset,mistercrunch/panoramix,airbnb/superset