java java.util.ConcurrentModificationException同时向apache jena添加属性

Question

嗨，我有这段代码给我带来麻烦：

df = df.resample('1min').mean()
df['fire_in_the_next_5_minutes'] = df['fire'].bfill(limit=5)
df
Out[173]: 
                     fire  fire_in_the_next_5_minutes
2016-03-16 23:20:00   1.0                         1.0
2016-03-16 23:21:00   NaN                         NaN
2016-03-16 23:22:00   NaN                         NaN
2016-03-16 23:23:00   NaN                         1.0
2016-03-16 23:24:00   NaN                         1.0
2016-03-16 23:25:00   NaN                         1.0
2016-03-16 23:26:00   NaN                         1.0
2016-03-16 23:27:00   NaN                         1.0
2016-03-16 23:28:00   1.0                         1.0
2016-03-16 23:29:00   NaN                         NaN
2016-03-16 23:30:00   NaN                         NaN
2016-03-16 23:31:00   NaN                         NaN
2016-03-16 23:32:00   NaN                         NaN
2016-03-16 23:33:00   NaN                         1.0
2016-03-16 23:34:00   NaN                         1.0
2016-03-16 23:35:00   NaN                         1.0
2016-03-16 23:36:00   NaN                         1.0
2016-03-16 23:37:00   NaN                         1.0
2016-03-16 23:38:00   1.0                         1.0

注释行是引发异常的行。知道为什么会这样吗？

这是整个错误输出：

StmtIterator iter2 = model.listStatements(new SimpleSelector(null, FOAF.family_name, (RDFNode) null) {
            public boolean selects(Statement s) {
                // return the statements whose object equal to the required place
                return s.getString().toLowerCase().equals(latin.toLowerCase());
            }
        });
        if (iter2.hasNext()) {
            while (iter2.hasNext()) {
                Statement s = iter2.nextStatement();
                // s.getSubject().addProperty(FOAF.family_name, maltese, "mt");
            }
        }

该问题似乎是由于我添加的属性与我正在搜索的属性相同，即：family_name