public static final String SYSTEM_USER = "system";

    public static final String EMPTY_USER_ID = "<empty>";

    public static final String CRAWLER_PROCESS_COMMAND_THREAD_DUMP = "thread_dump";

    public static final String FESS_THUMBNAIL_PATH = "fess.thumbnail.path";

    public static final String FESS_VAR_PATH = "fess.var.path";

        final String commandTimeoutStr = fessConfig.getSystemProperty("thumbnail.command.timeout");
        if (commandTimeoutStr != null) {
            commandTimeout = Long.valueOf(commandTimeoutStr);
        }
        final String commandDestroyTimeoutStr = fessConfig.getSystemProperty("thumbnail.command.destroy.timeout");
        if (commandDestroyTimeoutStr != null) {

    String PROCESSORS = "processors";

    /** The key of the configuration. e.g. java */
    String JAVA_COMMAND_PATH = "java.command.path";

    /** The key of the configuration. e.g. python */
    String PYTHON_COMMAND_PATH = "python.command.path";

    /** The key of the configuration. e.g. UTF-8 */
    String PATH_ENCODING = "path.encoding";

        final String id = form.id;
        crawlingInfoService.getCrawlingInfo(id).ifPresent(entity -> {
            try {
                processHelper.sendCommand(entity.getSessionId(), Constants.CRAWLER_PROCESS_COMMAND_THREAD_DUMP);
                saveInfo(messages -> messages.addSuccessPrintThreadDump(GLOBAL));
            } catch (final Exception e) {
                logger.warn("Failed to print a thread dump.", e);