presto-main/src/main/java/io/prestosql/execution/QueryManagerConfig.java/QueryManagerConfig/setRemoteTaskMaxCallbackThreads
class QueryManagerConfig:    @Config("query.remote-task.max-callback-threads")
    public QueryManagerConfig setRemoteTaskMaxCallbackThreads(int remoteTaskMaxCallbackThreads)
    {
        this.remoteTaskMaxCallbackThreads = remoteTaskMaxCallbackThreads;
        return this;
    }