A simple script to measure API Gateway endpoint latency. Requires Apache HttpComponents

Latency.java

@Test
public void testPerf() throws IOException {
    final HttpGet request = new HttpGet("https://[API-ID].execute-api.[REGION].amazonaws.com/[STAGE]/[PATH]");
    final int numRequests = 10000;
    final int[] histogram = new int[100];
    final List<Integer> latencies = new ArrayList<>();

    final CloseableHttpClient client = HttpClients.createDefault();

    for (int i = 0; i < numRequests; i++) {

        long start = System.currentTimeMillis();
        final CloseableHttpResponse resp = client.execute(request);
        resp.close();
        long millis = System.currentTimeMillis() - start;

        if (millis > 800) {
            LOG.warn(String.format("Request took %dms" + ", request ID: %s, CF request ID: %s", millis,
                                   resp.getFirstHeader("X-Amzn-Requestid"), resp.getFirstHeader("X-Amz-Cf-Id")));
        }

        histogram[((int) (millis / 100))]++;
        latencies.add((int) millis);
    }

    Collections.sort(latencies);

    final int p50 = latencies.get((50 * (numRequests) / 100) - 1);
    final int p90 = latencies.get((90 * (numRequests) / 100) - 1);
    final int p99 = latencies.get((99 * (numRequests) / 100) - 1);
    final int p100 = latencies.get((100 * (numRequests) / 100) - 1);

    LOG.info(String.format("Num requests: %d P50: %dms P90: %dms P99: %dms P100: %dms", numRequests, p50, p90, p99, p100));
    LOG.info(String.format("Distribution: "));
    for (int i = 0; i < histogram.length; i++) {
        LOG.info(i*100 + "ms - " + (i+1)*100 + "ms: " + histogram[i]);
    }
}