The commission, in its autumn economic forecast, said “the arrival of large numbers of asylum seekers” would require increases in public spending to manage the influx — spending that would provide a stimulus to the European economy.

There would also be an additional positive impact from the increase in workers, “provided the right policies are in place to facilitate access to the labor market,” the commission said in a news release.

Some analysts questioned whether the European Commission was being too optimistic in its forecast — whether because too few of the newcomers will have the right job skills or be young enough to make long-term contributions to the economy, or because too few countries are ready to absorb the migrants.

“Member states have very different philosophies about how soon migrants can actually be integrated into the labor market,” said Stephen Booth, the co-director of Open Europe, a research group in London. “Germany has been willing to allow those seeking asylum to take jobs more quickly than, say, countries like France.’’

The commission’s report acknowledged that the European recovery has been slow. And it warned against expectations of a rapid turnaround because of challenges that include the slowdown in China and regional tensions created by a standoff with Russia over Ukraine.