python fcntl不获取锁

我已经用python编写了一个在csv文件中并行编写的代码。 当我的程序结束时，我看到的是很少的行被合并，而不是在单独的行中。每行应仅包含3列。但它显示如下

乙二醇

通过阅读其他几个问题，我了解到，如果我想避免这种情况，我需要锁定我的文件。所以我添加了fcntl模块。但我的文件似乎仍然没有被锁定，因为它会产生类似的输出

我的代码

def getdata(x):
    try:
    # get data from API
        c.writefile(x,x1,x2)
except Exception,err:
    print err

class credits:
    def __init__(self):
        self.d = dict()
        self.details = dict()
        self.filename = "abc.csv"
        self.fileopen = open(self.filename,"w")

    def acquire(self):
        fcntl.flock (self.fileopen, fcntl.LOCK_EX)

    def release(self):
        fcntl.flock(self.fileopen, fcntl.LOCK_UN)

    def __del__(self):
        self.fileopen.close()

    def writefile(self,x,x1,x2,x3):
        try:
            self.acquire()
            self.fileopen.write(str(x)+","+str(x1)+","+str(x2)+"\n")
        except Exception, e:
            raise e
        finally:
            self.release()
if __name__ == '__main__':
    conn = psycopg2.connect()
    curr = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
    curr.execute("select * from emp")
    rows = curr.fetchall()

    listdata = []
    for each in rows:
        listdata.append(each[0])

    c = credits()
    p = Pool(processes = 5)
    results = p.map(getdata,listdata)
    conn.close()

---

我必须将getdata声明为顶级函数，否则它会给我“Cant pickle function”

为什么不在每个单独的进程中写入多个文件，然后合并它们？它的计算成本可能更高，但可以确保线程安全。

您是否禁用了文件缓冲区？@denfromufa-很抱歉，但我不确定是否理解您的意思。我怎么做？好的。我确实尝试在fileopen命令中添加1和0。但我在文件中看到的是纯粹的垃圾。我还尝试在write命令之后添加flush命令。但它仍然向我显示了garbageNext to write to file语句，将等效的print添加到console语句中，并查看它们是否匹配

def getdata(x):
    try:
    # get data from API
        c.writefile(x,x1,x2)
except Exception,err:
    print err

class credits:
    def __init__(self):
        self.d = dict()
        self.details = dict()
        self.filename = "abc.csv"
        self.fileopen = open(self.filename,"w")

    def acquire(self):
        fcntl.flock (self.fileopen, fcntl.LOCK_EX)

    def release(self):
        fcntl.flock(self.fileopen, fcntl.LOCK_UN)

    def __del__(self):
        self.fileopen.close()

    def writefile(self,x,x1,x2,x3):
        try:
            self.acquire()
            self.fileopen.write(str(x)+","+str(x1)+","+str(x2)+"\n")
        except Exception, e:
            raise e
        finally:
            self.release()
if __name__ == '__main__':
    conn = psycopg2.connect()
    curr = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
    curr.execute("select * from emp")
    rows = curr.fetchall()

    listdata = []
    for each in rows:
        listdata.append(each[0])

    c = credits()
    p = Pool(processes = 5)
    results = p.map(getdata,listdata)
    conn.close()