Question

我正在尝试模拟交易中的冲突。我还没有理解如何做到这一点，但我遇到了错误，

我使用clojure和任务运行gradle。 clojure代码看起来像这样

(ns com.lapots.functional.clojure.script
    (:gen-class))

(def value "V0")
(def tx-value (ref value))

(def thread-1
    (future
        (dosync
            (println "tx-value (thread-1) =>" @tx-value)
            (ref-set tx-value "V1")))) ; V1`

(def thread-2
    (future
        (dosync
            (println "tx-value (thread-2) =>" @tx-value)
            (ref-set tx-value "V2"))))
            (Thread/sleep 2000)
            (ref-set tx-value "V3"))))

(println @tx-value)
@thread-2 ; start first as waiting
@thread-1
(println @tx-value)

gradle文件看起来像这样

apply plugin: 'clojure-min'

clojure {
    aotCompile = true
    warnOnReflection = true
}

repositories {
    clojarsRepo()
}

dependencies {
    compile "org.clojure:clojure:$clojureVersion"
}

task runClojure(dependsOn: classes, type: JavaExec) {
    main = 'com.lapots.functional.clojure.script'
    classpath = sourceSets.main.runtimeClasspath
}

但是我收到了这个错误

tx-value (thread-1) => V0
tx-value (thread-2) => V1                      
Exception in thread "main" java.lang.IllegalStateException: No transaction running, compiling:(script.clj:19:13)
        at clojure.lang.Compiler$InvokeExpr.eval(Compiler.java:3657)
        at clojure.lang.Compiler.compile1(Compiler.java:7474)
        at clojure.lang.Compiler.compile(Compiler.java:7541)
        at clojure.lang.RT.compile(RT.java:406)
        at clojure.lang.RT.load(RT.java:451)
        at clojure.lang.RT.load(RT.java:419)
        at clojure.core$load$fn__5677.invoke(core.clj:5893)
        at clojure.core$load.invokeStatic(core.clj:5892)
        at clojure.core$load.doInvoke(core.clj:5876)
        at clojure.lang.RestFn.invoke(RestFn.java:408)
        at clojure.core$load_one.invokeStatic(core.clj:5697)
        at clojure.core$compile$fn__5682.invoke(core.clj:5903)
        at clojure.core$compile.invokeStatic(core.clj:5903)
        at clojure.core$compile.invoke(core.clj:5895)
        at clojuresque.tasks.compile$eval41$main_task_driver__43$fn__47.invoke(compile.clj:16)
        at clojuresque.tasks.compile$eval41$main_task_driver__43.invoke(compile.clj:13)
        at clojuresque.tasks.compile$eval41$main__56.invoke(compile.clj:5)
        at clojure.lang.AFn.applyToHelper(AFn.java:152)
        at clojure.lang.AFn.applyTo(AFn.java:144)
        at clojure.core$apply.invokeStatic(core.clj:646)
        at clojure.core$apply.invoke(core.clj:641)
        at clojure.lang.Var.invoke(Var.java:383)
        at clojuresque.Driver.main(Driver.java:49)
Caused by: java.lang.IllegalStateException: No transaction running
        at clojure.lang.LockingTransaction.getEx(LockingTransaction.java:208)
        at clojure.lang.Ref.set(Ref.java:162)
        at clojure.core$ref_set.invokeStatic(core.clj:2352)
        at clojure.core$ref_set.invoke(core.clj:2346)
        at clojure.lang.AFn.applyToHelper(AFn.java:156)
        at clojure.lang.AFn.applyTo(AFn.java:144)
        at clojure.lang.Compiler$InvokeExpr.eval(Compiler.java:3652)
        ... 22 more

有什么问题？

Answer 1

def thread-2 dosync有非常无意义的parens，所以在你认为自己之前就关闭了(def thread-2 (future (dosync (println "tx-value (thread-2) =>" @tx-value) (ref-set tx-value "V2") (Thread/sleep 2000) (ref-set tx-value "V3"))))块。

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java.lang.IllegalStateException：没有事务正在运行

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