Italian Plum/ brown specks inside
Inner NE Portland Italian plum produced bumper crop this year, after two prior years of piddling amount. Tree is about 10 years old. Gets SE exposure. Generally, all trees (fruiting or not) are about 2-3 weeks behind others in my general neighborhood, due to shading. It's just starting to ripen now. Some fruit is falling now, but most on tree seem hard, and when cut open, are clearly not ripe. Most of the fruit I've cut so far have quite a lot of small brown specks inside, about the size of a fruit fly. The specks do not look like bug invasion to me. Instead, they seem to originate at the pit, and spread radially. Although none of the fruit is ripe at present, it does not seem to matter what degree of ripeness, the specks are in perhaps 75%. Thanks!
Multnomah County Oregon
I suspect a bacterial or fungus problem that starts with and at the flower stage of the plums development. Considering the shady location and your weather this is going to be a recurring problem. There isn't any commercial plant medicines to spray the tree with to prevent this in the future.