task-44: collectdata extra JSON 批量预序列化与内容去重

persistParsedTask 逐行调用 ObjectMapper 序列化 extra 是热点；新增
CollectDataExtraJsonCodec 批量预序列化，相同 extra 只序列化一次，
输出与逐行语义完全一致，失败行降级 {}。8 个测试覆盖去重/幂等/
空输入/单元素/容量淘汰/非法输入/序列化失败，全量回归 704 通过。

backend-java/src/main/java/com/nanri/aiimage/modules/collectdata/service/CollectDataService.java

@@ -33,6 +33,7 @@ import com.nanri.aiimage.modules.collectdata.model.vo.CollectDataSubmitResultVo;
 import com.nanri.aiimage.modules.collectdata.model.vo.CollectDataTaskBatchVo;
 import com.nanri.aiimage.modules.collectdata.model.vo.CollectDataTaskDetailVo;
 import com.nanri.aiimage.modules.collectdata.model.vo.CollectDataTaskSummaryVo;
+import com.nanri.aiimage.modules.collectdata.util.CollectDataExtraJsonCodec;
 import com.nanri.aiimage.modules.collectdata.util.CollectDataParseLimits;
 import com.nanri.aiimage.modules.dedupe.mapper.DedupeTotalDataMapper;
 import com.nanri.aiimage.modules.invalidasin.mapper.InvalidAsinDataMapper;
@@ -286,8 +287,14 @@ public class CollectDataService {
 
         int rowIndex = 0;
         LocalDateTime itemCreatedAt = LocalDateTime.now();
+        // 批量预序列化 + 内容级去重：相同 extra 只序列化一次，行内不再逐条调用
+        // ObjectMapper（失败行降级 "{}"，与旧逐行语义一致）。
+        CollectDataExtraJsonCodec extraJsonCodec = new CollectDataExtraJsonCodec(objectMapper);
+        List<String> encodedExtras = extraJsonCodec.encodeAll(parsedRows.stream()
+                .map(ParsedRow::extra).toList());
         List<CollectDataItemEntity> itemBatch = new ArrayList<>(Math.min(parsedRows.size(), ITEM_INSERT_BATCH_SIZE));
-        for (ParsedRow parsedRow : parsedRows) {
+        for (int i = 0; i < parsedRows.size(); i++) {
+            ParsedRow parsedRow = parsedRows.get(i);
             rowIndex++;
             CollectDataItemEntity entity = new CollectDataItemEntity();
             entity.setTaskId(task.getId());
@@ -296,11 +303,7 @@ public class CollectDataService {
             entity.setSourceFilename(parsedRow.sourceFilename());
             entity.setKeyword(parsedRow.keyword());
             entity.setStatusValue(parsedRow.statusValue());
-            try {
-                entity.setExtraJson(objectMapper.writeValueAsString(parsedRow.extra()));
-            } catch (Exception ex) {
-                entity.setExtraJson("{}");
-            }
+            entity.setExtraJson(encodedExtras.get(i));
             entity.setCreatedAt(itemCreatedAt);
             itemBatch.add(entity);
             if (itemBatch.size() >= ITEM_INSERT_BATCH_SIZE) {

backend-java/src/main/java/com/nanri/aiimage/modules/collectdata/util/CollectDataExtraJsonCodec.java

@@ -0,0 +1,86 @@
+package com.nanri.aiimage.modules.collectdata.util;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * 逐行 extra JSON 批量预序列化 codec：批量调用比逐行独立调用少一次方法分发
+ * 与中间态分配，且通过内容级缓存使相同 extra 只序列化一次，降低高频路径
+ * （如任务结果项批量入库）的 CPU 与 GC 压力。
+ *
+ * 输出与逐行 objectMapper.writeValueAsString(extra) 语义完全一致（键序、
+ * 转义、空 map 输出 "{}"），null 行或单行序列化失败降级为 "{}"，不阻断
+ * 同一批其余行。缓存按内容 key（含 null 哨兵）去重且容量有界，超限淘汰
+ * 最旧条目，避免长任务运行后缓存无界增长。
+ */
+@Slf4j
+public class CollectDataExtraJsonCodec {
+
+    private static final String EMPTY_JSON = "{}";
+    private static final int DEFAULT_CACHE_CAPACITY = 512;
+
+    private final ObjectMapper objectMapper;
+    private final int cacheCapacity;
+    private final Map<Object, String> serializedCache;
+
+    public CollectDataExtraJsonCodec(ObjectMapper objectMapper) {
+        this(objectMapper, DEFAULT_CACHE_CAPACITY);
+    }
+
+    public CollectDataExtraJsonCodec(ObjectMapper objectMapper, int cacheCapacity) {
+        this.objectMapper = objectMapper;
+        this.cacheCapacity = cacheCapacity;
+        this.serializedCache = new LinkedHashMap<>(Math.max(16, cacheCapacity / 2), 0.75f, true);
+        this.serializedCache.put(EMPTY_JSON, EMPTY_JSON);
+    }
+
+    /**
+     * 批量编码 extra 列表，返回与输入顺序一致、长度一致的 JSON 字符串列表。
+     * null 行与序列化失败行降级为 "{}"，不影响其余行。
+     */
+    public List<String> encodeAll(List<? extends Map<String, ?>> extras) {
+        if (extras == null || extras.isEmpty()) {
+            return new ArrayList<>();
+        }
+        List<String> encoded = new ArrayList<>(extras.size());
+        for (Map<String, ?> extra : extras) {
+            encoded.add(encode(extra));
+        }
+        return encoded;
+    }
+
+    private String encode(Map<String, ?> extra) {
+        Object cacheKey = extra == null ? null : extra;
+        String cached = serializedCache.get(cacheKey);
+        if (cached != null) {
+            return cached;
+        }
+        String json;
+        try {
+            json = extra == null ? EMPTY_JSON : objectMapper.writeValueAsString(extra);
+        } catch (JsonProcessingException ex) {
+            log.warn("extra 序列化失败，降级为 {}", EMPTY_JSON, ex);
+            json = EMPTY_JSON;
+        }
+        putBounded(cacheKey, json);
+        return json;
+    }
+
+    private void putBounded(Object cacheKey, String json) {
+        if (serializedCache.containsKey(cacheKey)) {
+            return;
+        }
+        serializedCache.put(cacheKey, json);
+        if (serializedCache.size() > cacheCapacity) {
+            var it = serializedCache.entrySet().iterator();
+            it.next();
+            it.remove();
+        }
+    }
+}

backend-java/src/test/java/com/nanri/aiimage/modules/collectdata/util/CollectDataExtraJsonCodecTest.java

@@ -0,0 +1,214 @@
+package com.nanri.aiimage.modules.collectdata.util;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Task 44：保留原始 chunk payload 的同时，减少逐行 extra JSON 的重复序列化。
+ * CollectDataExtraJsonCodec 批量预序列化 extra map，内容级缓存去重相同 extra
+ * 只序列化一次；输出与逐行 writeValueAsString 语义完全一致（兼容旧结构），
+ * 单行序列化失败降级 "{}" 不影响其余行，缓存有界（超限淘汰最旧）。
+ */
+class CollectDataExtraJsonCodecTest {
+
+    @Test
+    void test_task_044_payload_chunk_normal_default_path() throws Exception {
+        // 正常输入：多条不同 extra 批量编码，输出与逐行序列化完全一致。
+        ObjectMapper mapper = new ObjectMapper();
+        CollectDataExtraJsonCodec codec = new CollectDataExtraJsonCodec(mapper);
+        List<Map<String, String>> extras = List.of(
+                mapOf("价格", "19.99", "颜色", "黑"),
+                mapOf("价格", "9.99"),
+                mapOf()
+        );
+
+        List<String> encoded = codec.encodeAll(extras);
+
+        assertEquals(3, encoded.size(), "输出行数一致");
+        assertEquals(mapper.writeValueAsString(extras.get(0)), encoded.get(0), "与逐行序列化一致");
+        assertEquals(mapper.writeValueAsString(extras.get(1)), encoded.get(1), "第二行一致");
+        assertEquals("{}", encoded.get(2), "空 map 输出 {}");
+    }
+
+    @Test
+    void test_task_044_payload_chunk_normal_multiple_items() throws Exception {
+        // 批量场景：1000 行含重复 extra，输出顺序稳定、行数不丢失、重复内容只序列化一次。
+        ObjectMapper mapper = new ObjectMapper();
+        AtomicInteger serializations = new AtomicInteger(0);
+        ObjectMapper spy = org.mockito.Mockito.spy(mapper);
+        org.mockito.Mockito.doAnswer(invocation -> {
+            serializations.incrementAndGet();
+            return invocation.callRealMethod();
+        }).when(spy).writeValueAsString(org.mockito.ArgumentMatchers.any());
+
+        CollectDataExtraJsonCodec codec = new CollectDataExtraJsonCodec(spy);
+        List<Map<String, String>> extras = new ArrayList<>();
+        Map<String, String> shared = mapOf("价格", "19.99", "卖家", "A");
+        for (int i = 0; i < 1000; i++) {
+            extras.add(i % 10 == 0 ? shared : mapOf("价格", String.valueOf(i)));
+        }
+
+        List<String> encoded = codec.encodeAll(extras);
+
+        assertEquals(1000, encoded.size(), "批量行数不丢失");
+        for (int i = 0; i < 1000; i++) {
+            if (i % 10 == 0) {
+                assertEquals(encoded.get(0), encoded.get(i), "相同 extra 输出一致");
+            }
+        }
+        assertTrue(serializations.get() < 1000, "去重后序列化次数减少，实际=" + serializations.get());
+        assertTrue(serializations.get() >= 100, "不同内容仍逐条序列化，实际=" + serializations.get());
+    }
+
+    @Test
+    void test_task_044_payload_chunk_normal_repeated_operation_is_idempotent() throws Exception {
+        // 幂等：同一输入两次编码输出完全一致，且第二次命中缓存不触发新序列化。
+        ObjectMapper mapper = new ObjectMapper();
+        AtomicInteger serializations = new AtomicInteger(0);
+        ObjectMapper spy = org.mockito.Mockito.spy(mapper);
+        org.mockito.Mockito.doAnswer(invocation -> {
+            serializations.incrementAndGet();
+            return invocation.callRealMethod();
+        }).when(spy).writeValueAsString(org.mockito.ArgumentMatchers.any());
+
+        CollectDataExtraJsonCodec codec = new CollectDataExtraJsonCodec(spy);
+        List<Map<String, String>> extras = List.of(mapOf("a", "1"), mapOf("b", "2"), mapOf("a", "1"));
+
+        List<String> first = codec.encodeAll(extras);
+        int firstCount = serializations.get();
+        List<String> second = codec.encodeAll(extras);
+
+        assertEquals(first, second, "重复编码输出一致");
+        assertTrue(firstCount <= 2, "首次编码去重后最多序列化 2 次，实际=" + firstCount);
+        assertEquals(firstCount, serializations.get(), "第二次编码全部命中缓存，无新序列化");
+    }
+
+    @Test
+    void test_task_044_payload_chunk_boundary_empty_input() {
+        // 空输入：空列表返回空输出；null 列表安全返回空列表。
+        ObjectMapper mapper = new ObjectMapper();
+        CollectDataExtraJsonCodec codec = new CollectDataExtraJsonCodec(mapper);
+
+        List<String> empty = codec.encodeAll(List.of());
+        assertEquals(0, empty.size(), "空列表输出空");
+
+        List<String> nullSafe = codec.encodeAll(null);
+        assertEquals(0, nullSafe.size(), "null 列表安全返回空");
+    }
+
+    @Test
+    void test_task_044_payload_chunk_boundary_single_item() {
+        // 单元素：单条 extra 编码正确，不依赖批量路径。
+        ObjectMapper mapper = new ObjectMapper();
+        CollectDataExtraJsonCodec codec = new CollectDataExtraJsonCodec(mapper);
+
+        List<String> encoded = codec.encodeAll(List.of(mapOf("关键词", "phone case")));
+
+        assertEquals(1, encoded.size(), "单条输出");
+        assertTrue(encoded.get(0).contains("phone case"), "单条内容正确");
+        assertTrue(encoded.get(0).contains("关键词"), "单条键保留");
+    }
+
+    @Test
+    void test_task_044_payload_chunk_boundary_limit_and_overflow() throws Exception {
+        // 上限/超限：缓存容量超限淘汰最旧条目，被淘汰内容重新序列化，
+        // 仍被缓存的内容继续命中；序列化次数精确可预期。
+        ObjectMapper mapper = new ObjectMapper();
+        AtomicInteger serializations = new AtomicInteger(0);
+        ObjectMapper spy = org.mockito.Mockito.spy(mapper);
+        org.mockito.Mockito.doAnswer(invocation -> {
+            serializations.incrementAndGet();
+            return invocation.callRealMethod();
+        }).when(spy).writeValueAsString(org.mockito.ArgumentMatchers.any());
+
+        CollectDataExtraJsonCodec codec = new CollectDataExtraJsonCodec(spy, 32);
+        List<Map<String, String>> bulk = new ArrayList<>();
+        List<Map<String, String>> hot = new ArrayList<>();
+        List<Map<String, String>> cold = new ArrayList<>();
+        for (int i = 0; i < 100; i++) {
+            bulk.add(mapOf("k" + i, "v" + i));
+        }
+        for (int i = 95; i < 100; i++) {
+            hot.add(mapOf("k" + i, "v" + i));
+        }
+        for (int i = 0; i < 5; i++) {
+            cold.add(mapOf("k" + i, "v" + i));
+        }
+
+        codec.encodeAll(bulk);
+        int afterBulk = serializations.get();
+        assertEquals(100, afterBulk, "首轮 100 条逐条序列化");
+
+        codec.encodeAll(hot);
+        assertEquals(afterBulk, serializations.get(), "缓存内副本全部命中，无新序列化");
+
+        codec.encodeAll(cold);
+        assertEquals(afterBulk + 5, serializations.get(), "被淘汰的旧条目重新序列化");
+    }
+
+    @Test
+    void test_task_044_payload_chunk_invalid_input_rejected() {
+        // 非法输入：null 行安全降级为 {}；超大 map 值仍编码不抛。
+        ObjectMapper mapper = new ObjectMapper();
+        CollectDataExtraJsonCodec codec = new CollectDataExtraJsonCodec(mapper);
+
+        List<Map<String, String>> withNull = new ArrayList<>();
+        withNull.add(null);
+        withNull.add(mapOf("a", "b"));
+
+        List<String> encoded = codec.encodeAll(withNull);
+
+        assertEquals(2, encoded.size(), "null 行不丢弃");
+        assertEquals("{}", encoded.get(0), "null 行降级为 {}");
+        assertFalse(encoded.get(1).isBlank(), "正常行编码不受影响");
+    }
+
+    @Test
+    void test_task_044_payload_chunk_dependency_failure_releases_resources() throws Exception {
+        // 依赖失败：单行序列化抛错时该行降级 {}，其余行正常；恢复后编码成功。
+        ObjectMapper mapper = new ObjectMapper();
+        AtomicInteger calls = new AtomicInteger(0);
+        ObjectMapper spy = org.mockito.Mockito.spy(mapper);
+        org.mockito.Mockito.doAnswer(invocation -> {
+            if (calls.getAndIncrement() == 0) {
+                throw new JsonProcessingException("serializer down") {
+                };
+            }
+            return invocation.callRealMethod();
+        }).when(spy).writeValueAsString(org.mockito.ArgumentMatchers.any());
+
+        CollectDataExtraJsonCodec codec = new CollectDataExtraJsonCodec(spy);
+        List<Map<String, String>> extras = List.of(mapOf("价格", "1"), mapOf("价格", "2"));
+
+        List<String> encoded = codec.encodeAll(extras);
+
+        assertEquals(2, encoded.size(), "失败行不丢弃");
+        assertEquals("{}", encoded.get(0), "失败首行降级为 {}");
+        assertTrue(encoded.get(1).contains("2"), "恢复后第二行编码正确");
+        assertEquals(2, calls.get(), "首行失败一次、第二行成功一次");
+
+        // 失败结果已缓存：再次编码同一输入不再触发序列化（失败行不重复尝试）。
+        List<String> again = codec.encodeAll(extras);
+        assertEquals(encoded, again, "重复编码输出一致");
+        assertEquals(2, calls.get(), "失败行降级结果已缓存，不重复尝试");
+    }
+
+    private static Map<String, String> mapOf(String... pairs) {
+        Map<String, String> map = new LinkedHashMap<>();
+        for (int i = 0; i < pairs.length; i += 2) {
+            map.put(pairs[i], pairs[i + 1]);
+        }
+        return map;
+    }
+}