Trying to figure out why this code hangs. I can remove any one of the 3 lines at the bottom of the test and it won't hang, but all 3 together makes it hang. Any help would be greatly appreciated!
[Fact]
public async Task CanAddValuesInParallel() {
var muxer = ConnectionMultiplexer.Connect("localhost");
var db = muxer.GetDatabase();
await AddAsync(db, "test", "1");
await db.KeyDeleteAsync("test");
Task.Run(() => AddAsync(db, "test", "1")).Wait();
}
public async Task<bool> AddAsync(IDatabase db, string key, string value) {
return await db.StringSetAsync(key, value, null, When.NotExists);
}
It sounds to me like a sync-context deadlock from mixing Wait
and await
. Which is why you never do that - (switching into "Gilbert and Sullivan"): well, hardly ever!
If it helps, I suspect that removing the await
in the Wait
subtree will fix it - which should be trivial since that tree can be replaced with a trivial pass-thru:
public Task<bool> AddAsync(IDatabase db, string key, string value) {
return db.StringSetAsync(key, value, null, When.NotExists);
}
The important point here is that SE.Redis bypasses sync-context internally (normal for library code), so it shouldn't have the deadlock.
But ultimately: mixing Wait
and await
is not a good idea. In addition to deadlocks, this is "sync over async" - an anti-pattern.
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