{html.escape(node.text)}'
+ # 文档级累计复杂度预算：超出后回退占位，不再采样求值
+ if self._plot_nodes + parsed.plot.node_count > _MAX_TOTAL_PLOT_NODES:
+ warnings.append(
+ f"函数图像：文档内函数图像累计复杂度超过上限 {_MAX_TOTAL_PLOT_NODES} 节点，已回退为源码占位"
+ )
+ return f'{html.escape(node.text)}'
+ self._plot_nodes += parsed.plot.node_count
rendered = render_svg(parsed.plot)
except Exception as exc:
warnings.append(f"函数图像：解析或渲染失败，已回退占位（{exc}）")
diff --git a/backend/app/export/service.py b/backend/app/export/service.py
index 13a8117..ca3efa6 100644
--- a/backend/app/export/service.py
+++ b/backend/app/export/service.py
@@ -43,6 +43,10 @@ MAX_JOBS = 100
MAX_MARKDOWN_CHARS = 200_000
# 最终导出产物大小上限，防止超大 HTML 耗尽内存/磁盘
MAX_EXPORT_BYTES = 20 * 1024 * 1024 # 20 MB
+# 并发渲染上限：解析/渲染是 CPU 密集的同步工作，限制同时执行的任务数，
+# 防止大量任务同时占满工作线程与内存
+MAX_CONCURRENT_RENDERS = 2
+_render_slots = asyncio.Semaphore(MAX_CONCURRENT_RENDERS)
# 产物有效期
FILE_TTL = timedelta(hours=24)
@@ -208,47 +212,50 @@ async def _execute(
}
)
try:
- # 让出一次，使「创建后立即取消」的 queued 任务能及时进入 cancelled
- await asyncio.sleep(0)
- if cancel_event.is_set():
- raise ExportCancelled()
+ # 并发渲染限额：解析/渲染是 CPU 密集的同步工作，用信号量限制同时执行的任务数，
+ # 超出限额的任务在此排队等待，避免大量任务同时占满工作线程与内存
+ async with _render_slots:
+ # 让出一次，使「创建后立即取消」的 queued 任务能及时进入 cancelled
+ await asyncio.sleep(0)
+ if cancel_event.is_set():
+ raise ExportCancelled()
- # 解析与渲染都是 CPU 密集的同步工作，放入线程执行避免阻塞事件循环，
- # 使运行中的取消能在渲染边界生效；写文件前再次检查取消。
- document = await asyncio.to_thread(parse_document, markdown)
- document.attributes["title"] = title
- if metadata:
- document.attributes["metadata"] = metadata
+ # 解析与渲染都是 CPU 密集的同步工作，放入线程执行避免阻塞事件循环，
+ # 使运行中的取消能在渲染边界生效；写文件前再次检查取消。
+ document = await asyncio.to_thread(parse_document, markdown)
+ document.attributes["title"] = title
+ if metadata:
+ document.attributes["metadata"] = metadata
- result = await asyncio.to_thread(_render_document, document, options)
- if cancel_event.is_set():
- raise ExportCancelled()
- if len(result.content) > MAX_EXPORT_BYTES:
- raise ExportTooLarge()
+ result = await asyncio.to_thread(_render_document, document, options)
+ if cancel_event.is_set():
+ raise ExportCancelled()
+ if len(result.content) > MAX_EXPORT_BYTES:
+ raise ExportTooLarge()
- out_dir = get_settings().exports_path
- out_dir.mkdir(parents=True, exist_ok=True)
- path = _export_path(job_id)
- path.write_bytes(result.content)
+ out_dir = get_settings().exports_path
+ out_dir.mkdir(parents=True, exist_ok=True)
+ path = _export_path(job_id)
+ path.write_bytes(result.content)
- completed_at = _now()
- _jobs[job_id] = _jobs[job_id].model_copy(
- update={
- "status": ExportStatus.completed,
- "progress": ExportProgress(
- phase="completed", current=1, total=1, percent=1.0
- ),
- "file": ExportFile(
- file_name=f"{_safe_download_name(title)}.html",
- mime_type=result.mime_type,
- size=len(result.content),
- sha256=hashlib.sha256(result.content).hexdigest(),
- expires_at=completed_at + FILE_TTL,
- ),
- "warnings": result.warnings,
- "completed_at": completed_at,
- }
- )
+ completed_at = _now()
+ _jobs[job_id] = _jobs[job_id].model_copy(
+ update={
+ "status": ExportStatus.completed,
+ "progress": ExportProgress(
+ phase="completed", current=1, total=1, percent=1.0
+ ),
+ "file": ExportFile(
+ file_name=f"{_safe_download_name(title)}.html",
+ mime_type=result.mime_type,
+ size=len(result.content),
+ sha256=hashlib.sha256(result.content).hexdigest(),
+ expires_at=completed_at + FILE_TTL,
+ ),
+ "warnings": result.warnings,
+ "completed_at": completed_at,
+ }
+ )
except ExportCancelled:
_jobs[job_id] = _jobs[job_id].model_copy(
update={
diff --git a/backend/app/plot/model.py b/backend/app/plot/model.py
index 979577e..f11273e 100644
--- a/backend/app/plot/model.py
+++ b/backend/app/plot/model.py
@@ -31,6 +31,8 @@ class FunctionPlot(BaseModel):
domain: tuple[float, float] = (-10.0, 10.0)
range: tuple[float, float] | None = None
axes: PlotAxes = Field(default_factory=PlotAxes)
+ # 该块所有表达式 AST 节点数之和，供导出器做文档级累计复杂度预算
+ node_count: int = 0
class PlotDiagnostic(BaseModel):
diff --git a/backend/app/plot/parser.py b/backend/app/plot/parser.py
index 46a9984..4dab231 100644
--- a/backend/app/plot/parser.py
+++ b/backend/app/plot/parser.py
@@ -215,6 +215,13 @@ def parse_expression(expr: str) -> ast.Expression:
return tree
+def _count_nodes(node: ast.AST) -> int:
+ """统计已通过校验的表达式 AST 节点数，供文档级累计复杂度预算使用。"""
+ counter = [0]
+ _check_node(node, counter=counter)
+ return counter[0]
+
+
def evaluate(expr_ast: ast.Expression, x: float) -> float:
"""递归解释已校验 AST 得到数值，全程不编译/执行代码。"""
return _eval_node(expr_ast.body, x)
@@ -282,6 +289,7 @@ def parse_source(source: str) -> FunctionPlotParseResult:
ylabel: str | None = None
grid: bool = True
has_error = False
+ total_nodes = 0
for lineno, raw_line in enumerate(source.splitlines(), start=1):
line = raw_line.strip()
@@ -363,12 +371,13 @@ def parse_source(source: str) -> FunctionPlotParseResult:
continue
try:
- parse_expression(expr_text)
+ tree = parse_expression(expr_text)
except PlotParseError as exc:
exc.diagnostic.line = lineno
diagnostics.append(exc.diagnostic)
has_error = True
continue
+ total_nodes += _count_nodes(tree.body)
expressions.append(FunctionPlotExpression(expression=expr_text))
# 表达式数量超限：整块回退并提前终止，避免对海量表达式做采样求值
if len(expressions) > _MAX_EXPRESSIONS:
@@ -398,5 +407,6 @@ def parse_source(source: str) -> FunctionPlotParseResult:
domain=domain,
range=range_,
axes=PlotAxes(xlabel=xlabel, ylabel=ylabel, grid=grid),
+ node_count=total_nodes,
)
return FunctionPlotParseResult(plot=plot, diagnostics=diagnostics)
diff --git a/backend/tests/test_export.py b/backend/tests/test_export.py
index a00383d..1d95ad1 100644
--- a/backend/tests/test_export.py
+++ b/backend/tests/test_export.py
@@ -449,3 +449,37 @@ def test_export_output_too_large(monkeypatch) -> None:
assert finished.error_code == "EXPORT_OUTPUT_TOO_LARGE"
assert finished.file is None
assert not (get_settings().exports_path / f"{finished.job_id}.html").exists()
+
+
+def test_export_limits_concurrent_rendering(monkeypatch) -> None:
+ # P1：并发渲染受 MAX_CONCURRENT_RENDERS 限制，大量任务不会同时占满工作线程
+ import threading
+ import time
+
+ real_render = export_service._render_document
+ active = 0
+ peak = 0
+ lock = threading.Lock()
+
+ def slow_render(document, options):
+ nonlocal active, peak
+ with lock:
+ active += 1
+ peak = max(peak, active)
+ time.sleep(0.05)
+ with lock:
+ active -= 1
+ return real_render(document, options)
+
+ monkeypatch.setattr(export_service, "_render_document", slow_render)
+
+ async def _go():
+ jobs = [
+ await export_service.create_export(_markdown_request(f"# t{i}"))
+ for i in range(6)
+ ]
+ return [await export_service.wait_for_export(j.job_id) for j in jobs]
+
+ finished = asyncio.run(_go())
+ assert all(j.status == ExportStatus.completed for j in finished)
+ assert peak <= export_service.MAX_CONCURRENT_RENDERS
diff --git a/backend/tests/test_plot.py b/backend/tests/test_plot.py
index cd95a46..4537e04 100644
--- a/backend/tests/test_plot.py
+++ b/backend/tests/test_plot.py
@@ -269,3 +269,17 @@ def test_html_exporter_limits_function_plot_count() -> None:
assert html.count('') == 4
assert any("函数图像数量超过上限" in w for w in result.warnings)
+
+
+def test_html_exporter_limits_total_plot_nodes(monkeypatch) -> None:
+ # P1：文档级累计 AST 节点预算超限后，后续图像回退占位，防止组合复杂度耗尽 CPU
+ import app.export.exporters.html as html_mod
+
+ monkeypatch.setattr(html_mod, "_MAX_TOTAL_PLOT_NODES", 5)
+ # 第一个图块 y=x（1 节点）在预算内；第二个图块 y=x+x+x+x（7 节点）累计超限
+ md = "```function-plot\ny = x\n```\n\n```function-plot\ny = x + x + x + x\n```"
+ result = asyncio.run(HtmlExporter().export(parse_document(md), ExportOptions()))
+ html = result.content.decode("utf-8")
+ assert html.count('') == 1
+ assert html.count('') == 1
+ assert any("累计复杂度" in w for w in result.warnings)
diff --git a/docs/development/Export开发说明.md b/docs/development/Export开发说明.md
index 40a1a92..7edd783 100644
--- a/docs/development/Export开发说明.md
+++ b/docs/development/Export开发说明.md
@@ -63,20 +63,31 @@ fenced code 按语言分流：`mermaid` → `mermaid` 节点、`function_plot`/`
- 输入源（`note` 与 `markdown`）统一限制 `MAX_MARKDOWN_CHARS = 200_000` 字符，超限返回 `EXPORT_OPTIONS_INVALID`。
- 单个 `function-plot` 图块最多 16 条表达式，超限整块回退占位并记结构化诊断 `FUNCTION_PLOT_TOO_MANY_EXPRESSIONS`。
- 单篇文档最多 16 个函数图像，超出部分回退占位并记 warning。
+- 单篇文档累计函数图像 AST 节点预算 `_MAX_TOTAL_PLOT_NODES = 8000`，超出部分回退占位并记 warning，防止多图块 × 多表达式 × 深表达式组合在采样求值时长时间占满 CPU。
+- 并发渲染上限 `MAX_CONCURRENT_RENDERS = 2`，解析/渲染是 CPU 密集工作，超出限额的任务在内存中排队等待渲染槽位，避免大量任务同时占满工作线程与内存。
- 最终产物大小上限 `MAX_EXPORT_BYTES = 20 MB`，超限任务标记 failed 并返回 `EXPORT_OUTPUT_TOO_LARGE`。
## 错误码
+错误分两类：**同步错误**在创建/查询请求的 HTTP 响应里直接返回对应状态码；**异步任务错误**在创建时已返回 `202`，后续轮询 `GET /api/exports/{job_id}` 仍返回 `200`，错误通过任务状态与 `error_code` 字段暴露，**不映射 HTTP 状态码**。
+
+同步错误：
+
```text
EXPORT_SOURCE_NOT_FOUND 404
EXPORT_FORMAT_UNSUPPORTED 400
EXPORT_OPTIONS_INVALID 400
-EXPORT_RENDER_FAILED 500
-EXPORT_UNSUPPORTED_CONTENT 422
+EXPORT_UNSUPPORTED_CONTENT 422（预留）
EXPORT_JOB_NOT_FOUND 404
EXPORT_FILE_EXPIRED 410
EXPORT_CAPACITY_EXCEEDED 429
-EXPORT_OUTPUT_TOO_LARGE 413
+```
+
+异步任务错误（轮询返回 `200`，字段形如 `{"status": "failed", "error_code": "..."}`）：
+
+```text
+EXPORT_RENDER_FAILED
+EXPORT_OUTPUT_TOO_LARGE
```
## 测试