ss="n"><span class="pre">num_threads</span></span><span class="p"><span class="pre">:</span></span><span class="w"> </span><span class="n"><span class="pre">int</span></span><span class="w"> </span><span class="o"><span class="pre">=</span></span><span class="w"> </span><span class="default_value"><span class="pre">-1</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">query_ef</span></span><span class="p"><span class="pre">:</span></span><span class="w"> </span><span class="n"><span