"SecureTransport":  {strconv.FormatBool(r.TLS != nil)},
		"SourceIp":         {handlers.GetSourceIPRaw(r)},
		"UserAgent":        {r.UserAgent()},
		"Referer":          {r.Referer()},
		"principaltype":    {principalType},
		"userid":           {username},
		"username":         {username},
		"versionid":        {vid},
		"signatureversion": {signatureVersion},

        final FessConfig fessConfig = ComponentUtil.getFessConfig();

        if (!fessConfig.isAcceptedSearchReferer(request.getHeader("referer"))) {
            writeJsonResponse(HttpServletResponse.SC_BAD_REQUEST, escapeJsonKeyValue(MESSAGE_FIELD, "Referer is invalid."));
            return;
        }

        if (!fessConfig.isApiSearchScroll()) {

            return 1000;
        }

        @Override
        public String[] getSearchlogRequestHeadersAsArray() {
            return new String[] { "user-agent", "referer" };
        }

        @Override
        public boolean isLoggingSearchDocsEnabled() {
            return false;
        }

        @Override

        }
        if (patterns.length == 0) {
            return true;
        }

        if (referer == null) {
            return false;
        }
        return Arrays.stream(patterns).anyMatch(p -> p.matcher(referer).matches());
    }

    String getQueryHighlightContentDescriptionFields();

                    appendJson("query-page-size", entity.getQueryPageSize(), buf).append(',');
                    appendJson("query-offset", entity.getQueryOffset(), buf).append(',');
                    appendJson("referer", entity.getReferer(), buf).append(',');
                    appendJson("languages", entity.getLanguages(), buf).append(',');
                    appendJson("roles", entity.getRoles(), buf).append(',');

            searchLog.setClientIp(StringUtils.abbreviate(ComponentUtil.getViewHelper().getClientIp(req), 100));
            searchLog.setReferer(StringUtils.abbreviate(req.getHeader("referer"), 1000));
            searchLog.setUserAgent(StringUtils.abbreviate(req.getHeader("user-agent"), 255));
            final Object accessType = req.getAttribute(Constants.SEARCH_LOG_ACCESS_TYPE);

            params.put("Offset", toNumberString(e.getQueryOffset()));
            params.put("Page Size", toNumberString(e.getQueryPageSize()));
            params.put("Client IP", e.getClientIp());
            params.put("Referer", e.getReferer());
            params.put("Languages", e.getLanguages());
            params.put("Virtual Host", e.getVirtualHost());

Depois, ele 🤖 pega a primeira tarefa para finalizar (vamos dizer, nosso "arquivo lento" 📝) e continua o que tem que fazer com ela.

Esse "esperar por algo" normalmente se refere a operações <abbr title="Entrada e Saída">I/O</abbr> que são relativamente "lentas" (comparadas à velocidade do processador e da memória RAM), como esperar por:

* dados do cliente para serem enviados através da rede

            referents = new HashMap();
            referent = 1;
        }

        e = (Entry) referents.get(obj);
        if (e == null) {
            e = new Entry();
            e.referent = referent++;
            e.obj = obj;
            referents.put(obj, e);
        }

        return e.referent;
    }

    /**
     * Encodes an NDR referent pointer.
     *

 */
public class NdrBuffer {

    private int referent;
    private Map<Object, Entry> referents;

    private static class Entry {

        public Entry(final int referent, final Object obj) {
            this.referent = referent;
            this.obj = obj;
        }

        final int referent;

        @SuppressWarnings("unused")
        private final Object obj;
    }