我有一组需要扩展的项目，所以我选择 reactor 是因为它的反应能力，因为扩展需要 IO 操作。这是一段工作代码：public Flux<Item> expand(List<Item> unprocessedItems) { return Flux.fromIterable(unprocessedItems) .expandDeep(this::expandItem);}请注意，这this::expandItem是一个阻塞操作（多个数据库查询，一些计算，...）。现在我希望这个扩展是平行的，但据我所知.expand()，.expandDeep()并且只是班级的成员，Flux而不是ParallelFlux班级的成员。我尝试在通话之前添加.publishOn()and ，但没有运气。.subscribeOn().expand()这是我第一次使用反应器，但我没有看到任何阻止并行扩展的技术问题，有什么办法吗？API是否丢失或我错过了什么？
2 回答
狐的传说
TA贡献1804条经验 获得超3个赞
是的，你是对的ParallelFluxhas not .expand()and .expandDeep()methods，但我可以使用其他方式，创建具有扩展方法的附加 Publisher 并将其传递给你的ParallelFlux，如下所示：
public static void main(String[] args) {
Function<Node, Flux<Node>> expander =
node -> Flux.fromIterable(node.children);
List<Node> roots = createTestNodes();
Flux.fromIterable(roots)
.parallel(4)
.runOn(Schedulers.parallel())
.flatMap(node -> Flux.just(node).expandDeep(expander))
.doOnNext(i -> System.out.println("Time: " + System.currentTimeMillis() + " thread: " + Thread.currentThread().getName() + " value: " + i))
.sequential()
.subscribe();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("finished");
}
我的测试数据：
static final class Node {
final String name;
final List<Node> children;
Node(String name, Node... nodes) {
this.name = name;
this.children = new ArrayList<>();
children.addAll(Arrays.asList(nodes));
}
@Override
public String toString() {
return name;
}
}
static List<Node> createTestNodes() {
return new Node("root",
new Node("1",
new Node("11")
),
new Node("2",
new Node("21"),
new Node("22",
new Node("221")
)
),
new Node("3",
new Node("31"),
new Node("32",
new Node("321")
),
new Node("33",
new Node("331"),
new Node("332",
new Node("3321")
)
)
),
new Node("4",
new Node("41"),
new Node("42",
new Node("421")
),
new Node("43",
new Node("431"),
new Node("432",
new Node("4321")
)
),
new Node("44",
new Node("441"),
new Node("442",
new Node("4421")
),
new Node("443",
new Node("4431"),
new Node("4432")
)
)
)
).children;
}
结果：
Time: 1549296674522 thread: parallel-4 value: 4
Time: 1549296674523 thread: parallel-4 value: 41
Time: 1549296674523 thread: parallel-2 value: 2
Time: 1549296674523 thread: parallel-2 value: 21
Time: 1549296674523 thread: parallel-3 value: 3
Time: 1549296674523 thread: parallel-3 value: 31
Time: 1549296674523 thread: parallel-1 value: 1
Time: 1549296674523 thread: parallel-1 value: 11
Time: 1549296674525 thread: parallel-2 value: 22
Time: 1549296674525 thread: parallel-2 value: 221
Time: 1549296674526 thread: parallel-3 value: 32
Time: 1549296674526 thread: parallel-3 value: 321
Time: 1549296674526 thread: parallel-3 value: 33
Time: 1549296674526 thread: parallel-3 value: 331
Time: 1549296674526 thread: parallel-3 value: 332
Time: 1549296674526 thread: parallel-3 value: 3321
Time: 1549296674526 thread: parallel-4 value: 42
Time: 1549296674526 thread: parallel-4 value: 421
Time: 1549296674526 thread: parallel-4 value: 43
Time: 1549296674526 thread: parallel-4 value: 431
Time: 1549296674526 thread: parallel-4 value: 432
Time: 1549296674526 thread: parallel-4 value: 4321
Time: 1549296674527 thread: parallel-4 value: 44
Time: 1549296674527 thread: parallel-4 value: 441
Time: 1549296674527 thread: parallel-4 value: 442
Time: 1549296674527 thread: parallel-4 value: 4421
Time: 1549296674528 thread: parallel-4 value: 443
Time: 1549296674528 thread: parallel-4 value: 4431
Time: 1549296674528 thread: parallel-4 value: 4432
如您所见expander，在并行线程中工作。
ibeautiful
TA贡献1993条经验 获得超6个赞
这是一个示例，基于YauhenBalykin给出的示例：
public static void main(String[] args) {
Function<Node, Flux<Node>> expander =
node -> Flux.fromIterable(node.children)
.subscribeOn(Schedulers.parallel());
List<Node> roots = createTestNodes();
Flux.fromIterable(roots)
.expand(expander)
.doOnNext(i -> System.out.println("Time: " + System.currentTimeMillis() + " thread: " + Thread.currentThread().getName() + " value: " + i))
.subscribe();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("finished");
}
测试数据：
static final class Node {
final String name;
final List<Node> children;
Node(String name, Node... nodes) {
this.name = name;
this.children = new ArrayList<>();
children.addAll(Arrays.asList(nodes));
}
@Override
public String toString() {
return name;
}
}
static List<Node> createTestNodes() {
return new Node("root",
new Node("1",
new Node("11")
),
new Node("2",
new Node("21"),
new Node("22",
new Node("221")
)
),
new Node("3",
new Node("31"),
new Node("32",
new Node("321")
),
new Node("33",
new Node("331"),
new Node("332",
new Node("3321")
)
)
),
new Node("4",
new Node("41"),
new Node("42",
new Node("421")
),
new Node("43",
new Node("431"),
new Node("432",
new Node("4321")
)
),
new Node("44",
new Node("441"),
new Node("442",
new Node("4421")
),
new Node("443",
new Node("4431"),
new Node("4432")
)
)
)
).children;
}
结果：
Time: 1636182895717 thread: main value: 1
Time: 1636182895754 thread: main value: 2
Time: 1636182895754 thread: main value: 3
Time: 1636182895754 thread: main value: 4
Time: 1636182895761 thread: parallel-1 value: 11
Time: 1636182895761 thread: parallel-2 value: 21
Time: 1636182895761 thread: parallel-2 value: 22
Time: 1636182895762 thread: parallel-3 value: 31
Time: 1636182895762 thread: parallel-3 value: 32
Time: 1636182895762 thread: parallel-3 value: 33
Time: 1636182895762 thread: parallel-4 value: 41
Time: 1636182895762 thread: parallel-4 value: 42
Time: 1636182895762 thread: parallel-4 value: 43
Time: 1636182895762 thread: parallel-4 value: 44
Time: 1636182895764 thread: parallel-7 value: 221
Time: 1636182895764 thread: parallel-9 value: 321
Time: 1636182895764 thread: parallel-10 value: 331
Time: 1636182895765 thread: parallel-10 value: 332
Time: 1636182895765 thread: parallel-12 value: 421
Time: 1636182895765 thread: parallel-1 value: 431
Time: 1636182895765 thread: parallel-1 value: 432
Time: 1636182895766 thread: parallel-2 value: 441
Time: 1636182895766 thread: parallel-2 value: 442
Time: 1636182895766 thread: parallel-2 value: 443
Time: 1636182895766 thread: parallel-6 value: 3321
Time: 1636182895767 thread: parallel-9 value: 4321
Time: 1636182895767 thread: parallel-11 value: 4421
Time: 1636182895767 thread: parallel-12 value: 4431
Time: 1636182895767 thread: parallel-12 value: 4432
finished
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