alibaba/canal · error · RuntimeException

requestGet remote error, request : {}

Error message

requestGet remote error, request : {}

What it means

Outer catch in HttpHelper.get() (HttpHelper.java:99-100): catches any Throwable from the entire GET flow and rethrows it wrapped in a new RuntimeException 'requestGet remote error, request : <url>' with the original as the cause. This is the exception callers actually observe. It covers: the inner non-200 throw (error 356, preserved as cause), connect failures (unknown host, connection refused), socket/connect/request timeouts from RequestConfig, IllegalArgument/State exceptions from URIBuilder, and NullPointerException if httpclient is null (httpclient is left null when the SSLContext builder in the constructor throws, whose own catch silently ignores the error).

Source

Thrown at instance/manager/src/main/java/com/alibaba/otter/canal/instance/manager/plain/HttpHelper.java:100

            if (heads != null) {
                for (Map.Entry<String, String> entry : heads.entrySet()) {
                    httpGet.setHeader(entry.getKey(), entry.getValue());
                }
            }

            HttpClientContext context = HttpClientContext.create();
            context.setRequestConfig(config);
            response = httpclient.execute(httpGet, context);
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == HttpStatus.SC_OK) {
                return EntityUtils.toString(response.getEntity());
            } else {
                String errorMsg = EntityUtils.toString(response.getEntity());
                throw new RuntimeException("requestGet remote error, url=" + uri.toString() + ", code=" + statusCode
                                           + ", error msg=" + errorMsg);
            }
        } catch (Throwable t) {
            throw new RuntimeException("requestGet remote error, request : " + url, t);
        } finally {
            if (response != null) {
                try {
                    response.close();
                } catch (IOException e) {
                    // ignore
                }
            }
            if (httpGet != null) {
                httpGet.releaseConnection();
            }
        }
    }

    public String post(String url, Map<String, String> heads, Object requestBody, int timeout) {
        return post0(url, heads, JSON.toJSONString(requestBody), timeout);
    }

View on GitHub (pinned to 87be50e876)

Solutions

1. Inspect the cause (getCause()) to classify: ConnectException/UnknownHostException → network/DNS; SocketTimeoutException → raise timeout or fix manager latency; the inner 'requestGet remote error, url=..., code=...' → handle per error 356; NullPointerException → httpclient was not built (constructor SSL init failed) — restart and check HttpClient/SSL dependencies.
2. Verify the manager URL and that the manager is reachable from the canal node: curl -v <manager-url>.
3. Increase the timeout passed to get() if the manager is slow.
4. Ensure the JVM has the crypto libraries needed for SSLContextBuilder in the HttpHelper constructor; otherwise httpclient stays null and every call NPEs.
5. Add monitoring/alerting on this RuntimeException to catch manager connectivity loss early.

// Validate manager reachability and that httpclient was built (constructor SSL init can leave it null)
if (helper == null) throw new IllegalStateException("HttpHelper not initialized");
try (java.net.Socket s = new java.net.Socket()) {
    s.connect(new InetSocketAddress(new URL(managerBaseUrl).getHost(),
              new URL(managerBaseUrl).getPort() > 0 ? new URL(managerBaseUrl).getPort() : 80), 3000);
} catch (Exception e) {
    throw new IllegalStateException("manager host unreachable: " + managerBaseUrl, e);
}

try {
    String body = helper.get(url, heads, timeout);
} catch (RuntimeException e) {
    Throwable c = e.getCause();
    if (c instanceof java.net.SocketTimeoutException) {
        log.warn("manager GET timeout to {} (timeout={}ms) — raise timeout or check manager load", url, timeout);
    } else if (c != null && c.getMessage() != null && c.getMessage().contains("code=")) {
        log.error("manager GET non-200: {}", c.getMessage()); // see error 356
    } else if (c instanceof NullPointerException) {
        log.error("httpclient was null — HttpHelper constructor SSL init failed; restart and verify crypto deps");
    } else {
        log.error("manager GET failed to {}", url, e);
    }
    throw e;
}

When it happens

Trigger: Any failure during HttpHelper.get() — non-200 response, network unreachable, timeout (connect/socket/connection-request all set to `timeout`), malformed URL, or httpclient null due to constructor SSL failure. The outer catch wraps all of them uniformly.

Common situations: canal-manager host unreachable / DNS failure; manager down or overloaded; request timeout too low for the manager response; URL misconfigured in canal.properties; httpclient null because SSLContext init failed silently in the constructor (then httpclient.execute throws NPE); network firewall dropping the manager connection.

Related errors

• requestPost remote error, request : {}
• requestGet remote error, url={}, code={}, error msg={}
• requestPost remote error, request : {}, statusCode={};{}
• requestGet remote error, request : {}
• requestPost remote error, request : {}

AI-assisted analysis of alibaba/canal@87be50e876 (2026-08-14). Data as JSON: /api/errors/ed1ee75a401f51ff. Report an issue: GitHub.