(live-crawler) Use Apache HttpClient + code cleanup

The fix makes sure we wait for the feeds API to be available before fetching from it, so that the process doesn't crash on a cold system reboot.

code/functions/live-capture/api/java/nu/marginalia/api/feeds/FeedsClient.java

@@ -11,6 +11,7 @@ import nu.marginalia.service.discovery.property.ServicePartition;
 import nu.marginalia.service.module.ServiceConfiguration;
 
 import javax.annotation.CheckReturnValue;
+import java.time.Duration;
 import java.time.Instant;
 import java.util.ArrayList;
 import java.util.List;
@@ -59,6 +60,11 @@ public class FeedsClient {
                 .forEachRemaining(rsp -> consumer.accept(rsp.getDomain(), new ArrayList<>(rsp.getUrlList())));
     }
 
+    public boolean waitReady(Duration duration) throws InterruptedException {
+        return channelPool.awaitChannel(duration);
+    }
+
+
     /** Get the hash of the feed data, for identifying when the data has been updated */
     public String getFeedDataHash() {
         return channelPool.call(FeedApiGrpc.FeedApiBlockingStub::getFeedDataHash)

code/processes/live-crawling-process/build.gradle

@@ -50,6 +50,7 @@ dependencies {
 
     implementation libs.notnull
     implementation libs.guava
+    implementation libs.httpclient
     implementation dependencies.create(libs.guice.get()) {
         exclude group: 'com.google.guava'
     }

code/processes/live-crawling-process/java/nu/marginalia/livecrawler/LiveCrawlerMain.java

@@ -15,6 +15,7 @@ import nu.marginalia.coordination.DomainCoordinator;
 import nu.marginalia.db.DbDomainQueries;
 import nu.marginalia.db.DomainBlacklist;
 import nu.marginalia.io.SerializableCrawlDataStream;
+import nu.marginalia.livecrawler.io.HttpClientProvider;
 import nu.marginalia.loading.LoaderInputData;
 import nu.marginalia.loading.documents.DocumentLoaderService;
 import nu.marginalia.loading.documents.KeywordLoaderService;
@@ -32,12 +33,15 @@ import nu.marginalia.service.module.ServiceDiscoveryModule;
 import nu.marginalia.storage.FileStorageService;
 import nu.marginalia.storage.model.FileStorageBaseType;
 import org.apache.commons.io.FileUtils;
+import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
+import org.apache.hc.core5.io.CloseMode;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.security.Security;
+import java.time.Duration;
 import java.time.Instant;
 import java.time.temporal.ChronoUnit;
 import java.util.HashMap;
@@ -74,7 +78,9 @@ public class LiveCrawlerMain extends ProcessMainClass {
                            DomainProcessor domainProcessor,
                            FileStorageService fileStorageService,
                            KeywordLoaderService keywordLoaderService,
-                           DocumentLoaderService documentLoaderService, DomainCoordinator domainCoordinator, HikariDataSource dataSource)
+                           DocumentLoaderService documentLoaderService,
+                           DomainCoordinator domainCoordinator,
+                           HikariDataSource dataSource)
             throws Exception
     {
         super(messageQueueFactory, config, gson, LIVE_CRAWLER_INBOX);
@@ -148,7 +154,10 @@ public class LiveCrawlerMain extends ProcessMainClass {
     }
 
     private void run() throws Exception {
-        Path basePath = fileStorageService.getStorageBase(FileStorageBaseType.STORAGE).asPath().resolve("live-crawl-data");
+        Path basePath = fileStorageService
+                .getStorageBase(FileStorageBaseType.STORAGE)
+                .asPath()
+                .resolve("live-crawl-data");
 
         if (!Files.isDirectory(basePath)) {
             Files.createDirectories(basePath);
@@ -163,21 +172,38 @@ public class LiveCrawlerMain extends ProcessMainClass {
         {
             final Instant cutoff = Instant.now().minus(60, ChronoUnit.DAYS);
 
+            /* ------------------------------------------------ */
+            /* Fetch the latest domains from the feeds database */
+            /* ------------------------------------------------ */
+
             processHeartbeat.progress(LiveCrawlState.FETCH_LINKS);
 
             Map<String, List<String>> urlsPerDomain = new HashMap<>(10_000);
+            if (!feedsClient.waitReady(Duration.ofHours(1))) {
+                throw new RuntimeException("Feeds client never became ready, cannot proceed with live crawling");
+            }
             feedsClient.getUpdatedDomains(cutoff, urlsPerDomain::put);
 
             logger.info("Fetched data for {} domains", urlsPerDomain.size());
 
+
+            /* ------------------------------------- */
+            /* Prune the database from old entries   */
+            /* ------------------------------------- */
+
             processHeartbeat.progress(LiveCrawlState.PRUNE_DB);
 
-            // Remove data that is too old
             dataSet.prune(cutoff);
 
+
+            /* ------------------------------------- */
+            /* Fetch the links for each domain       */
+            /* ------------------------------------- */
+
             processHeartbeat.progress(LiveCrawlState.CRAWLING);
 
-            try (SimpleLinkScraper fetcher = new SimpleLinkScraper(dataSet, domainCoordinator, domainQueries, domainBlacklist);
+            CloseableHttpClient client = HttpClientProvider.createClient();
+            try (SimpleLinkScraper fetcher = new SimpleLinkScraper(dataSet, domainCoordinator, domainQueries, client, domainBlacklist);
                  var hb = heartbeat.createAdHocTaskHeartbeat("Live Crawling"))
             {
                 for (Map.Entry<String, List<String>> entry : hb.wrap("Fetching", urlsPerDomain.entrySet())) {
@@ -190,18 +216,29 @@ public class LiveCrawlerMain extends ProcessMainClass {
                     fetcher.scheduleRetrieval(domain, urls);
                 }
             }
+            finally {
+                client.close(CloseMode.GRACEFUL);
+            }
 
             Path tempPath = dataSet.createWorkDir();
 
+
             try {
+                /* ------------------------------------- */
+                /* Process the fetched links             */
+                /* ------------------------------------- */
+
                 processHeartbeat.progress(LiveCrawlState.PROCESSING);
 
                 try (var hb = heartbeat.createAdHocTaskHeartbeat("Processing");
                      var writer = new ConverterBatchWriter(tempPath, 0)
                 ) {
-                    // Offset the documents' ordinals toward the upper range, to avoid an ID collisions with the
-                    // main indexes (the maximum permissible for doc ordinal is  value is 67_108_863, so this
-                    // leaves us with a lot of headroom still)
+                    // We need unique document ids that do not collide with the document id from the main index,
+                    // so we offset the documents' ordinals toward the upper range.
+                    //
+                    // The maximum permissible for doc ordinal is value is 67_108_863,
+                    // so this leaves us with a lot of headroom still!
+                    // Expected document count here is order of 10 :^)
                     writer.setOrdinalOffset(67_000_000);
 
                     for (SerializableCrawlDataStream stream : hb.wrap("Processing", dataSet.getDataStreams())) {
@@ -209,10 +246,15 @@ public class LiveCrawlerMain extends ProcessMainClass {
                     }
                 }
 
+
+                /* ---------------------------------------------- */
+                /* Load the processed data into the link database */
+                /* and construct an index journal for the docs    */
+                /* ---------------------------------------------- */
+
                 processHeartbeat.progress(LiveCrawlState.LOADING);
 
                 LoaderInputData lid = new LoaderInputData(tempPath, 1);
-
                 DomainIdRegistry domainIdRegistry = new DbDomainIdRegistry(dataSource);
 
                 keywordLoaderService.loadKeywords(domainIdRegistry, heartbeat, lid);
@@ -224,9 +266,16 @@ public class LiveCrawlerMain extends ProcessMainClass {
                 FileUtils.deleteDirectory(tempPath.toFile());
             }
 
-            // Construct the index
+
+            /* ------------------------------------- */
+            /*  Finish up                            */
+            /* ------------------------------------- */
 
             processHeartbeat.progress(LiveCrawlState.DONE);
+
+            // After we return from here, the LiveCrawlActor will trigger an index construction
+            // job.  Unlike all the stuff we did in this process, it's identical to the real job
+            // so we don't need to do anything special from this process
         }
     }
 

code/processes/live-crawling-process/java/nu/marginalia/livecrawler/SimpleLinkScraper.java

@@ -7,7 +7,6 @@ import nu.marginalia.contenttype.ContentType;
 import nu.marginalia.contenttype.DocumentBodyToString;
 import nu.marginalia.coordination.DomainCoordinator;
 import nu.marginalia.coordination.DomainLock;
-import nu.marginalia.crawl.fetcher.HttpFetcherImpl;
 import nu.marginalia.crawl.retreival.CrawlDelayTimer;
 import nu.marginalia.db.DbDomainQueries;
 import nu.marginalia.db.DomainBlacklist;
@@ -15,24 +14,21 @@ import nu.marginalia.link_parser.LinkParser;
 import nu.marginalia.model.EdgeDomain;
 import nu.marginalia.model.EdgeUrl;
 import nu.marginalia.util.SimpleBlockingThreadPool;
+import org.apache.hc.client5.http.classic.HttpClient;
+import org.apache.hc.core5.http.ClassicHttpRequest;
+import org.apache.hc.core5.http.io.entity.EntityUtils;
+import org.apache.hc.core5.http.io.support.ClassicRequestBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import javax.annotation.Nullable;
-import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.net.URISyntaxException;
-import java.net.http.HttpClient;
-import java.net.http.HttpHeaders;
-import java.net.http.HttpRequest;
-import java.net.http.HttpResponse;
-import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
-import java.util.zip.GZIPInputStream;
 
 /** A simple link scraper that fetches URLs and stores them in a database,
  * with no concept of a crawl frontier, WARC output, or other advanced features
@@ -45,20 +41,21 @@ public class SimpleLinkScraper implements AutoCloseable {
     private final LiveCrawlDataSet dataSet;
     private final DbDomainQueries domainQueries;
     private final DomainBlacklist domainBlacklist;
-    private final Duration connectTimeout = Duration.ofSeconds(10);
-    private final Duration readTimeout = Duration.ofSeconds(10);
     private final DomainCoordinator domainCoordinator;
 
     private final static int MAX_SIZE = Integer.getInteger("crawler.maxFetchSize", 10 * 1024 * 1024);
+    private final HttpClient httpClient;
 
     public SimpleLinkScraper(LiveCrawlDataSet dataSet,
                              DomainCoordinator domainCoordinator,
                              DbDomainQueries domainQueries,
+                             HttpClient httpClient,
                              DomainBlacklist domainBlacklist) {
         this.dataSet = dataSet;
         this.domainCoordinator = domainCoordinator;
         this.domainQueries = domainQueries;
         this.domainBlacklist = domainBlacklist;
+        this.httpClient = httpClient;
     }
 
     public void scheduleRetrieval(EdgeDomain domain, List<String> urls) {
@@ -75,17 +72,19 @@ public class SimpleLinkScraper implements AutoCloseable {
 
         EdgeUrl rootUrl = domain.toRootUrlHttps();
 
-        List<EdgeUrl> relevantUrls = new ArrayList<>();
+        List<EdgeUrl> relevantUrls = new ArrayList<>(Math.max(1, urls.size()));
 
+        // Resolve absolute URLs
         for (var url : urls) {
             Optional<EdgeUrl> optParsedUrl = lp.parseLink(rootUrl, url);
-            if (optParsedUrl.isEmpty()) {
+
+            if (optParsedUrl.isEmpty())
                 continue;
-            }
-            if (dataSet.hasUrl(optParsedUrl.get())) {
-                continue;
-            }
-            relevantUrls.add(optParsedUrl.get());
+
+            EdgeUrl absoluteUrl = optParsedUrl.get();
+
+            if (!dataSet.hasUrl(absoluteUrl))
+                relevantUrls.add(absoluteUrl);
         }
 
         if (relevantUrls.isEmpty()) {
@@ -94,16 +93,10 @@ public class SimpleLinkScraper implements AutoCloseable {
 
         int fetched = 0;
 
-        try (HttpClient client = HttpClient
-                .newBuilder()
-                .connectTimeout(connectTimeout)
-                .followRedirects(HttpClient.Redirect.NEVER)
-                .version(HttpClient.Version.HTTP_2)
-                .build();
-             // throttle concurrent access per domain; IDE will complain it's not used, but it holds a semaphore -- do not remove:
+        try (// throttle concurrent access per domain; IDE will complain it's not used, but it holds a semaphore -- do not remove:
              DomainLock lock = domainCoordinator.lockDomain(domain)
         ) {
-            SimpleRobotRules rules = fetchRobotsRules(rootUrl, client);
+            SimpleRobotRules rules = fetchRobotsRules(rootUrl);
 
             if (rules == null) { // I/O error fetching robots.txt
                 // If we can't fetch the robots.txt,
@@ -116,18 +109,19 @@ public class SimpleLinkScraper implements AutoCloseable {
             CrawlDelayTimer timer = new CrawlDelayTimer(rules.getCrawlDelay());
 
             for (var parsedUrl : relevantUrls) {
-
                 if (!rules.isAllowed(parsedUrl.toString())) {
                     maybeFlagAsBad(parsedUrl);
                     continue;
                 }
 
-                switch (fetchUrl(domainId, parsedUrl, timer, client)) {
+                switch (fetchUrl(domainId, parsedUrl, timer)) {
                     case FetchResult.Success(int id, EdgeUrl docUrl, String body, String headers) -> {
                             dataSet.saveDocument(id, docUrl, body, headers, "");
                             fetched++;
                     }
-                    case FetchResult.Error(EdgeUrl docUrl) -> maybeFlagAsBad(docUrl);
+                    case FetchResult.Error(EdgeUrl docUrl) -> {
+                        maybeFlagAsBad(docUrl);
+                    }
                 }
             }
         }
@@ -150,111 +144,107 @@ public class SimpleLinkScraper implements AutoCloseable {
     }
 
     @Nullable
-    private SimpleRobotRules fetchRobotsRules(EdgeUrl rootUrl, HttpClient client) throws IOException, InterruptedException, URISyntaxException {
-        var robotsRequest = HttpRequest.newBuilder(rootUrl.withPathAndParam("/robots.txt", null).asURI())
-                .GET()
-                .header("User-Agent", WmsaHome.getUserAgent().uaString())
-                .header("Accept-Encoding","gzip")
-                .timeout(readTimeout);
-
-        // Fetch the robots.txt
+    private SimpleRobotRules fetchRobotsRules(EdgeUrl rootUrl) throws URISyntaxException {
+        ClassicHttpRequest request = ClassicRequestBuilder.get(rootUrl.withPathAndParam("/robots.txt", null).asURI())
+                .setHeader("User-Agent", WmsaHome.getUserAgent().uaString())
+                .setHeader("Accept-Encoding", "gzip")
+                .build();
 
         try {
-            SimpleRobotRulesParser parser = new SimpleRobotRulesParser();
-            HttpResponse<byte[]> robotsTxt = client.send(robotsRequest.build(), HttpResponse.BodyHandlers.ofByteArray());
-
-            if (robotsTxt.statusCode() == 200) {
-                return parser.parseContent(rootUrl.toString(),
-                        getResponseData(robotsTxt),
-                        robotsTxt.headers().firstValue("Content-Type").orElse("text/plain"),
-                        WmsaHome.getUserAgent().uaIdentifier());
+            return httpClient.execute(request, rsp -> {
+                if (rsp.getEntity() == null) {
+                    return null;
+                }
+                try {
+                    if (rsp.getCode() == 200) {
+                        var contentTypeHeader = rsp.getFirstHeader("Content-Type");
+                        if (contentTypeHeader == null) {
+                            return null; // No content type header, can't parse
+                        }
+                        return new SimpleRobotRulesParser().parseContent(
+                                rootUrl.toString(),
+                                EntityUtils.toByteArray(rsp.getEntity()),
+                                contentTypeHeader.getValue(),
+                                WmsaHome.getUserAgent().uaIdentifier()
+                        );
+                    } else if (rsp.getCode() == 404) {
+                        return new SimpleRobotRules(SimpleRobotRules.RobotRulesMode.ALLOW_ALL);
+                    }
+                } finally {
+                    EntityUtils.consumeQuietly(rsp.getEntity());
+                }
+                return null;
+            });
+        }
+        catch (IOException e) {
+            logger.error("Error fetching robots.txt for {}: {}", rootUrl, e.getMessage());
+            return null; // I/O error fetching robots.txt
+        }
+        finally {
+            try {
+                TimeUnit.SECONDS.sleep(1);
             }
-            else if (robotsTxt.statusCode() == 404) {
-                return new SimpleRobotRules(SimpleRobotRules.RobotRulesMode.ALLOW_ALL);
+            catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                throw new RuntimeException(e);
             }
         }
-        catch (IOException ex) {
-            logger.error("Error fetching robots.txt for {}: {} {}", rootUrl, ex.getClass().getSimpleName(), ex.getMessage());
-        }
-        return null;
     }
 
     /** Fetch a URL and store it in the database
      */
-    private FetchResult fetchUrl(int domainId, EdgeUrl parsedUrl, CrawlDelayTimer timer, HttpClient client) throws Exception {
+    private FetchResult fetchUrl(int domainId, EdgeUrl parsedUrl, CrawlDelayTimer timer) throws Exception {
 
-        timer.waitFetchDelay();
-
-        HttpRequest request = HttpRequest.newBuilder(parsedUrl.asURI())
-                .GET()
-                .header("User-Agent", WmsaHome.getUserAgent().uaString())
-                .header("Accept", "text/html")
-                .header("Accept-Encoding", "gzip")
-                .timeout(readTimeout)
+        ClassicHttpRequest request = ClassicRequestBuilder.get(parsedUrl.asURI())
+                .setHeader("User-Agent", WmsaHome.getUserAgent().uaString())
+                .setHeader("Accept", "text/html")
+                .setHeader("Accept-Encoding", "gzip")
                 .build();
 
         try {
-            HttpResponse<byte[]> response = client.send(request, HttpResponse.BodyHandlers.ofByteArray());
+            return httpClient.execute(request, rsp -> {
+                try {
+                    if (rsp.getCode() == 200) {
+                        String contentType = rsp.getFirstHeader("Content-Type").getValue();
+                        if (!contentType.toLowerCase().startsWith("text/html")) {
+                            return new FetchResult.Error(parsedUrl);
+                        }
 
-            // Handle rate limiting by waiting and retrying once
-            if (response.statusCode() == 429) {
-                timer.waitRetryDelay(new HttpFetcherImpl.RateLimitException(
-                        response.headers().firstValue("Retry-After").orElse("5")
-                ));
-                response = client.send(request, HttpResponse.BodyHandlers.ofByteArray());
-            }
+                        byte[] body = EntityUtils.toByteArray(rsp.getEntity(), MAX_SIZE);
 
-            String contentType = response.headers().firstValue("Content-Type").orElse("").toLowerCase();
+                        String bodyText = DocumentBodyToString.getStringData(ContentType.parse(contentType), body);
 
-            if (response.statusCode() == 200) {
-                if (!contentType.toLowerCase().startsWith("text/html")) {
-                    return new FetchResult.Error(parsedUrl);
+                        StringBuilder headersStr = new StringBuilder();
+                        for (var header : rsp.getHeaders()) {
+                            headersStr.append(header.getName()).append(": ").append(header.getValue()).append("\n");
+                        }
+
+                        return new FetchResult.Success(domainId, parsedUrl, bodyText, headersStr.toString());
+                    }
+                } finally {
+                    if (rsp.getEntity() != null) {
+                        EntityUtils.consumeQuietly(rsp.getEntity());
+                    }
                 }
-
-                byte[] body = getResponseData(response);
-                if (body.length > MAX_SIZE) {
-                    return new FetchResult.Error(parsedUrl);
-                }
-
-                String bodyText = DocumentBodyToString.getStringData(ContentType.parse(contentType), body);
-
-                return new FetchResult.Success(domainId, parsedUrl, bodyText, headersToString(response.headers()));
-            }
+                return new FetchResult.Error(parsedUrl);
+            });
         }
-        catch (IOException ex) {
-            // We don't want a full stack trace on every error, as it's quite common and very noisy
-            logger.error("Error fetching URL {}: {} {}", parsedUrl, ex.getClass().getSimpleName(), ex.getMessage());
+        catch (IOException e) {
+            logger.error("Error fetching {}: {}", parsedUrl, e.getMessage());
+            // If we can't fetch the URL, we return an error result
+            // so that the caller can decide what to do with it.
+        }
+        finally {
+            timer.waitFetchDelay();
         }
-
         return new FetchResult.Error(parsedUrl);
     }
 
-    private byte[] getResponseData(HttpResponse<byte[]> response) throws IOException {
-        String encoding = response.headers().firstValue("Content-Encoding").orElse("");
-
-        if ("gzip".equals(encoding)) {
-            try (var stream = new GZIPInputStream(new ByteArrayInputStream(response.body()))) {
-                return stream.readAllBytes();
-            }
-        }
-        else {
-            return response.body();
-        }
-    }
-
     sealed interface FetchResult {
         record Success(int domainId, EdgeUrl url, String body, String headers) implements FetchResult {}
         record Error(EdgeUrl url) implements FetchResult {}
     }
 
-    private String headersToString(HttpHeaders headers) {
-        StringBuilder headersStr = new StringBuilder();
-        headers.map().forEach((k, v) -> {
-            headersStr.append(k).append(": ").append(v).append("\n");
-        });
-        return headersStr.toString();
-    }
-
     @Override
     public void close() throws Exception {
         pool.shutDown();

code/processes/live-crawling-process/java/nu/marginalia/livecrawler/io/HttpClientProvider.java

@@ -0,0 +1,126 @@
+package nu.marginalia.livecrawler.io;
+
+import com.google.inject.Provider;
+import org.apache.hc.client5.http.ConnectionKeepAliveStrategy;
+import org.apache.hc.client5.http.classic.HttpClient;
+import org.apache.hc.client5.http.config.ConnectionConfig;
+import org.apache.hc.client5.http.config.RequestConfig;
+import org.apache.hc.client5.http.cookie.StandardCookieSpec;
+import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
+import org.apache.hc.client5.http.impl.classic.HttpClients;
+import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManager;
+import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManagerBuilder;
+import org.apache.hc.core5.http.HeaderElement;
+import org.apache.hc.core5.http.HeaderElements;
+import org.apache.hc.core5.http.HttpResponse;
+import org.apache.hc.core5.http.io.SocketConfig;
+import org.apache.hc.core5.http.message.MessageSupport;
+import org.apache.hc.core5.http.protocol.HttpContext;
+import org.apache.hc.core5.util.TimeValue;
+import org.apache.hc.core5.util.Timeout;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
+import java.util.Iterator;
+import java.util.concurrent.TimeUnit;
+
+public class HttpClientProvider implements Provider<HttpClient> {
+    private static final HttpClient client;
+    private static PoolingHttpClientConnectionManager connectionManager;
+
+    private static final Logger logger = LoggerFactory.getLogger(HttpClientProvider.class);
+
+    static {
+        try {
+            client = createClient();
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static CloseableHttpClient createClient() throws NoSuchAlgorithmException, KeyManagementException {
+        final ConnectionConfig connectionConfig = ConnectionConfig.custom()
+                .setSocketTimeout(15, TimeUnit.SECONDS)
+                .setConnectTimeout(15, TimeUnit.SECONDS)
+                .setValidateAfterInactivity(TimeValue.ofSeconds(5))
+                .build();
+
+
+        connectionManager = PoolingHttpClientConnectionManagerBuilder.create()
+                .setMaxConnPerRoute(2)
+                .setMaxConnTotal(50)
+                .setDefaultConnectionConfig(connectionConfig)
+                .build();
+
+        connectionManager.setDefaultSocketConfig(SocketConfig.custom()
+                .setSoLinger(TimeValue.ofSeconds(-1))
+                .setSoTimeout(Timeout.ofSeconds(10))
+                .build()
+        );
+
+        Thread.ofPlatform().daemon(true).start(() -> {
+            try {
+                for (;;) {
+                    TimeUnit.SECONDS.sleep(15);
+                    logger.info("Connection pool stats: {}", connectionManager.getTotalStats());
+                }
+            }
+            catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            }
+        });
+
+        final RequestConfig defaultRequestConfig = RequestConfig.custom()
+                .setCookieSpec(StandardCookieSpec.IGNORE)
+                .setResponseTimeout(10, TimeUnit.SECONDS)
+                .setConnectionRequestTimeout(5, TimeUnit.MINUTES)
+                .build();
+
+        return HttpClients.custom()
+                .setConnectionManager(connectionManager)
+                .setRetryStrategy(new RetryStrategy())
+                .setKeepAliveStrategy(new ConnectionKeepAliveStrategy() {
+                    // Default keep-alive duration is 3 minutes, but this is too long for us,
+                    // as we are either going to re-use it fairly quickly or close it for a long time.
+                    //
+                    // So we set it to 30 seconds or clamp the server-provided value to a minimum of 10 seconds.
+                    private static final TimeValue defaultValue = TimeValue.ofSeconds(30);
+
+                    @Override
+                    public TimeValue getKeepAliveDuration(HttpResponse response, HttpContext context) {
+                        final Iterator<HeaderElement> it = MessageSupport.iterate(response, HeaderElements.KEEP_ALIVE);
+
+                        while (it.hasNext()) {
+                            final HeaderElement he = it.next();
+                            final String param = he.getName();
+                            final String value = he.getValue();
+
+                            if (value == null)
+                                continue;
+                            if (!"timeout".equalsIgnoreCase(param))
+                                continue;
+
+                            try {
+                                long timeout = Long.parseLong(value);
+                                timeout = Math.clamp(timeout, 30, defaultValue.toSeconds());
+                                return TimeValue.ofSeconds(timeout);
+                            } catch (final NumberFormatException ignore) {
+                                break;
+                            }
+                        }
+                        return defaultValue;
+                    }
+                })
+                .disableRedirectHandling()
+                .setDefaultRequestConfig(defaultRequestConfig)
+                .build();
+    }
+
+    @Override
+    public HttpClient get() {
+        return client;
+    }
+}
+

code/processes/live-crawling-process/java/nu/marginalia/livecrawler/io/RetryStrategy.java

@@ -0,0 +1,79 @@
+package nu.marginalia.livecrawler.io;
+
+import org.apache.hc.client5.http.HttpHostConnectException;
+import org.apache.hc.client5.http.HttpRequestRetryStrategy;
+import org.apache.hc.core5.http.HttpRequest;
+import org.apache.hc.core5.http.HttpResponse;
+import org.apache.hc.core5.http.protocol.HttpContext;
+import org.apache.hc.core5.util.TimeValue;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.net.ssl.SSLException;
+import java.io.IOException;
+import java.net.SocketException;
+import java.net.SocketTimeoutException;
+import java.net.UnknownHostException;
+
+public class RetryStrategy implements HttpRequestRetryStrategy {
+    private static final Logger logger = LoggerFactory.getLogger(RetryStrategy.class);
+
+    @Override
+    public boolean retryRequest(HttpRequest request, IOException exception, int executionCount, HttpContext context) {
+        return switch (exception) {
+            case SocketTimeoutException ste -> false;
+            case SSLException ssle -> false;
+            case UnknownHostException uhe -> false;
+            case HttpHostConnectException ex -> executionCount < 2;
+            case SocketException ex -> executionCount < 2;
+            default -> executionCount <= 3;
+        };
+    }
+
+    @Override
+    public boolean retryRequest(HttpResponse response, int executionCount, HttpContext context) {
+        return switch (response.getCode()) {
+            case 500, 503 -> executionCount <= 2;
+            case 429 -> executionCount <= 3;
+            default -> false;
+        };
+    }
+
+    @Override
+    public TimeValue getRetryInterval(HttpRequest request, IOException exception, int executionCount, HttpContext context) {
+        return TimeValue.ofSeconds(1);
+    }
+
+    @Override
+    public TimeValue getRetryInterval(HttpResponse response, int executionCount, HttpContext context) {
+
+        int statusCode = response.getCode();
+
+        // Give 503 a bit more time
+        if (statusCode == 503) return TimeValue.ofSeconds(5);
+
+        if (statusCode == 429) {
+            // get the Retry-After header
+            var retryAfterHeader = response.getFirstHeader("Retry-After");
+            if (retryAfterHeader == null) {
+                return TimeValue.ofSeconds(3);
+            }
+
+            String retryAfter = retryAfterHeader.getValue();
+            if (retryAfter == null) {
+                return TimeValue.ofSeconds(2);
+            }
+
+            try {
+                int retryAfterTime = Integer.parseInt(retryAfter);
+                retryAfterTime = Math.clamp(retryAfterTime, 1, 5);
+
+                return TimeValue.ofSeconds(retryAfterTime);
+            } catch (NumberFormatException e) {
+                logger.warn("Invalid Retry-After header: {}", retryAfter);
+            }
+        }
+
+        return TimeValue.ofSeconds(2);
+    }
+}

code/processes/live-crawling-process/test/nu/marginalia/livecrawler/SimpleLinkScraperTest.java

@@ -3,10 +3,13 @@ package nu.marginalia.livecrawler;
 import nu.marginalia.coordination.LocalDomainCoordinator;
 import nu.marginalia.db.DomainBlacklistImpl;
 import nu.marginalia.io.SerializableCrawlDataStream;
+import nu.marginalia.livecrawler.io.HttpClientProvider;
 import nu.marginalia.model.EdgeDomain;
 import nu.marginalia.model.EdgeUrl;
 import nu.marginalia.model.crawldata.CrawledDocument;
 import org.apache.commons.io.FileUtils;
+import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
+import org.apache.hc.core5.io.CloseMode;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
@@ -16,29 +19,34 @@ import org.mockito.Mockito;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
 import java.sql.SQLException;
 import java.util.List;
 
 class SimpleLinkScraperTest {
     private Path tempDir;
     private LiveCrawlDataSet dataSet;
+    private CloseableHttpClient httpClient;
 
     @BeforeEach
-    public void setUp() throws IOException, SQLException {
+    public void setUp() throws IOException, SQLException, NoSuchAlgorithmException, KeyManagementException {
         tempDir = Files.createTempDirectory(getClass().getSimpleName());
         dataSet = new LiveCrawlDataSet(tempDir);
+        httpClient = HttpClientProvider.createClient();
     }
 
 
     @AfterEach
     public void tearDown() throws Exception {
         dataSet.close();
+        httpClient.close(CloseMode.IMMEDIATE);
         FileUtils.deleteDirectory(tempDir.toFile());
     }
 
     @Test
     public void testRetrieveNow() throws Exception {
-        var scraper = new SimpleLinkScraper(dataSet, new LocalDomainCoordinator(),  null, Mockito.mock(DomainBlacklistImpl.class));
+        var scraper = new SimpleLinkScraper(dataSet, new LocalDomainCoordinator(),  null, httpClient, Mockito.mock(DomainBlacklistImpl.class));
         int fetched = scraper.retrieveNow(new EdgeDomain("www.marginalia.nu"), 1, List.of("https://www.marginalia.nu/"));
         Assertions.assertEquals(1, fetched);
 
@@ -58,7 +66,7 @@ class SimpleLinkScraperTest {
     @Test
     public void testRetrieveNow_Redundant() throws Exception {
         dataSet.saveDocument(1, new EdgeUrl("https://www.marginalia.nu/"), "<html>", "", "127.0.0.1");
-        var scraper = new SimpleLinkScraper(dataSet, new LocalDomainCoordinator(),null, Mockito.mock(DomainBlacklistImpl.class));
+        var scraper = new SimpleLinkScraper(dataSet, new LocalDomainCoordinator(),null, httpClient, Mockito.mock(DomainBlacklistImpl.class));
 
         // If the requested URL is already in the dataSet, we retrieveNow should shortcircuit and not fetch anything
         int fetched = scraper.retrieveNow(new EdgeDomain("www.marginalia.nu"), 1, List.of("https://www.marginalia.nu/"));