2024 Spark 5063

The preservesPartitioning = true tells Spark that this map function doesn't modify the keys of rdd2; this will allow Spark to avoid re-partitioning rdd2 for any subsequent operations that join based on the (t, w) key. This broadcast could be inefficient since it involves a communications bottleneck at the driver. . Shark vertex vacuum won

17. You are passing a pyspark dataframe, df_whitelist to a UDF, pyspark dataframes cannot be pickled. You are also doing computations on a dataframe inside a UDF which is not acceptable (not possible). Keep in mind that your function is going to be called as many times as the number of rows in your dataframe, so you should keep computations ...This item: Denso (5063) K20TXR Traditional Spark Plug, Pack of 1. $674. +. Powerbuilt 12 Millimeter 7-1/2-Inch Jam Nut Valve Adjustment Tool, Slotted Valve Adjusting Stud, Honda, Nissan, Toyota Vehicle Engines - 648828. $2697.For more information, see SPARK-5063. _pickle.PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. 代码 For more information, see SPARK-5063. The objective of this piece of code is to create a flag for every row based on the date differences. Multiple rows per user are supplied to the function to create the values of the flag.Without the call of collect the Dataframe url_select_df is distributed across the executors. When you then call map, the lambda expression gets executed on the executors.. Because the lambda expression is calling createDF which is using the SparkContext you get the exception as it is not possible to use the SparkContext on an execThe issue is that, as self._mapping appears in the function addition, when applying addition_udf to the pyspark dataframe, the object self (i.e. the AnimalsToNumbers class) has to be serialized but it can’t be. A (surprisingly simple) way is to create a reference to the dictionary ( self._mapping) but not the object: AnimalsToNumbers (spark ...Using foreach to fill a list from Pyspark data frame. foreach () is used to iterate over the rows in a PySpark data frame and using this we are going to add the data from each row to a list. The foreach () function is an action and it is executed on the driver node and not on the worker nodes. This means that it is not recommended to use ...Jan 21, 2019 · Thread Pools. One of the ways that you can achieve parallelism in Spark without using Spark data frames is by using the multiprocessing library. The library provides a thread abstraction that you can use to create concurrent threads of execution. However, by default all of your code will run on the driver node. Dec 11, 2020 · Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. I also tried with the following (simple) neural network and command, and I receive EXACTLY the same error org.apache.spark.SparkException: RDD transformations and actions can only be invoked by the driver, not inside of other transformations; for example, rdd1.map (x => rdd2.values.count () * x) is invalid because the values transformation and count action cannot be performed inside of the rdd1.map transformation. For more information, see SPARK-5063.Mar 6, 2023 · Cannot create pyspark dataframe on pandas pipelinedRDD. list_of_df = process_pitd_objects (objects) # returns a list of dataframes list_rdd = sc.parallelize (list_of_df) spark_df_list = list_rdd.map (lambda x: spark.createDataFrame (x)).collect () So I have a list of dataframes in python and I want to convert each dataframe to pyspark. The preservesPartitioning = true tells Spark that this map function doesn't modify the keys of rdd2; this will allow Spark to avoid re-partitioning rdd2 for any subsequent operations that join based on the (t, w) key. This broadcast could be inefficient since it involves a communications bottleneck at the driver.May 5, 2022 · Error: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. Jun 23, 2017 · For more information, see SPARK-5063. (2) When a Spark Streaming job recovers from checkpoint, this exception will be hit if a reference to an RDD not defined by the streaming job is used in DStream operations. For more information, See SPARK-13758. For more information, see SPARK-5063. _pickle.PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. 代码 I want to broadcast a hashmap in Python that I would like to use for lookups on worker nodes. class datatransform: # Constructor def __init__(self, lookupFileName, dataFileName): ...For more information, see SPARK-5063. The objective of this piece of code is to create a flag for every row based on the date differences. Multiple rows per user are supplied to the function to create the values of the flag.Error: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063.Mar 26, 2020 · For more information, see SPARK-5063. 原因： spark不允许在action或transformation中访问SparkContext，如果你的action或transformation中引用了self，那么spark会将整个对象进行序列化，并将其发到工作节点上，这其中就保留了SparkContext，即使没有显式的访问它，它也会在闭包内被引用 ... def localCheckpoint (self): """ Mark this RDD for local checkpointing using Spark's existing caching layer. This method is for users who wish to truncate RDD lineages while skipping the expensive step of replicating the materialized data in a reliable distributed file system.spark.sql("select * from test") --need to pass select values as intput values to same function --used pandas df for calling function – pythonUser Feb 24, 2021 at 16:08Jan 2, 2020 · PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. Jun 26, 2018 · Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. #88 org.apache.spark.SparkException: RDD transformations and actions can only be invoked by the driver, not inside of other transformations; for example, rdd1.map (x => rdd2.values.count () * x) is invalid because the values transformation and count action cannot be performed inside of the rdd1.map transformation. For more information, see SPARK-5063.Apache Spark. Databricks Runtime 10.4 LTS includes Apache Spark 3.2.1. This release includes all Spark fixes and improvements included in Databricks Runtime 10.3 (Unsupported), as well as the following additional bug fixes and improvements made to Spark: [SPARK-38322] [SQL] Support query stage show runtime statistics in formatted explain mode.def localCheckpoint (self): """ Mark this RDD for local checkpointing using Spark's existing caching layer. This method is for users who wish to truncate RDD lineages while skipping the expensive step of replicating the materialized data in a reliable distributed file system.RDD transformations and actions can only be invoked by the driver, not inside of other transformations; for example, rdd1.map(lambda x: rdd2.values.count() * x) is invalid because the values transformation and count action cannot be performed inside of the rdd1.map transformation. For more information, see SPARK-5063.Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. Is there any way to run a SQL query for each row of a dataframe in PySpark?I'm trying to calculate the Pearson correlation between two DStreams using sliding window in Pyspark. But I keep getting the following error: Traceback (most recent call last): File "/home/zeinab/Jul 21, 2020 · For more information, see SPARK-5063. Super simple EXAMPLE app to try and run some calculations in parallel. Works (sometimes) but most times crashes with the above exception. Apache Spark. Databricks Runtime 10.4 LTS includes Apache Spark 3.2.1. This release includes all Spark fixes and improvements included in Databricks Runtime 10.3 (Unsupported), as well as the following additional bug fixes and improvements made to Spark: [SPARK-38322] [SQL] Support query stage show runtime statistics in formatted explain mode.df = spark.createDataFrame(data,schema=schema) Now we do two things. First, we create a function colsInt and register it. That registered function calls another function toInt (), which we don’t need to register. The first argument in udf.register (“colsInt”, colsInt) is the name we’ll use to refer to the function.May 2, 2015 · For more information, see SPARK-5063. As the error says, i'm trying to map (transformation) a JavaRDD object within the main map function, how is it possible with Apache Spark? The main JavaPairRDD object (TextFile and Word are defined classes): JavaPairRDD<TextFile, JavaRDD<Word>> filesWithWords = new... and map function: def localCheckpoint (self): """ Mark this RDD for local checkpointing using Spark's existing caching layer. This method is for users who wish to truncate RDD lineages while skipping the expensive step of replicating the materialized data in a reliable distributed file system.PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063.Aug 28, 2018 · SparkContext can only be used on the driver. When you invoke map you are on an Executor. The link I sent you runs parallel collection and is invoked from the Driver, also doing some zipping stuff. I discussed this with that person on that question as that is what became of it. That is the correct approach imho. I have a function that accepts a spark DataFrame and I would like to obtain the Spark context in which the DataFrames exists. The reason is that I want to get the SQLContext so I can run some SQL queries. sql_Context = SQLContext (output_df.sparkContext ()) sql_Context.registerDataFrameAsTable (output_df, "table1") sql_Context.sql ("select ...Jun 7, 2023 · RuntimeError: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. Labels: Broadcast variable. Sparkcontext. 2_image.png.png. 37 KB. this rdd lacks a sparkcontext. it could happen in the following cases: . rdd transformations and actions are not invoked by the driver, . but inside of other transformations; for example, rdd1.map(x => rdd2.values.count() * x) is invalid because the values transformation and count action cannot be performed inside of the rdd1.map transformationpyspark.SparkContext.broadcast. ¶. SparkContext.broadcast(value: T) → pyspark.broadcast.Broadcast [ T] [source] ¶. Broadcast a read-only variable to the cluster, returning a Broadcast object for reading it in distributed functions. The variable will be sent to each cluster only once. New in version 0.7.0. Parameters. valueT.As explained in the SPARK-5063 "Spark does not support nested RDDs". You are trying to access centroids (RDD) in map on sig_vecs (RDD): docs = sig_vecs.map(lambda x: k_means.classify_docs(x, centroids)) Converting centroids to a local collection (collect?) and adjusting classify_docs should address the problem.Sep 30, 2015 · org.apache.spark.SparkException: RDD transformations and actions can only be invoked by the driver, not inside of other transformations; for example, rdd1.map (x => rdd2.values.count () * x) is invalid because the values transformation and count action cannot be performed inside of the rdd1.map transformation. For more information, see SPARK-5063. Without the call of collect the Dataframe url_select_df is distributed across the executors. When you then call map, the lambda expression gets executed on the executors.. Because the lambda expression is calling createDF which is using the SparkContext you get the exception as it is not possible to use the SparkContext on an execAs explained in the SPARK-5063 "Spark does not support nested RDDs". You are trying to access centroids (RDD) in map on sig_vecs (RDD): docs = sig_vecs.map(lambda x: k_means.classify_docs(x, centroids)) Converting centroids to a local collection (collect?) and adjusting classify_docs should address the problem.Jan 31, 2023 · For more information, see SPARK-5063. During handling of the above exception, another exception occurred: raise pickle.PicklingError(msg) _pickle.PicklingError: Could not serialize broadcast: RuntimeError: It appears that you are attempting to reference SparkContext from a broadcast variable, .. etc Jan 3, 2022 · SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. from pyspark import SparkContext from awsglue.context import GlueContext from awsglue.transforms import SelectFields import ray import settings sc = SparkContext.getOrCreate () glue_context = GlueContext (sc) @ray.remote def ... Teams. Q&A for work. Connect and share knowledge within a single location that is structured and easy to search. Learn more about Teamsthis rdd lacks a sparkcontext. it could happen in the following cases: . rdd transformations and actions are not invoked by the driver, . but inside of other transformations; for example, rdd1.map(x => rdd2.values.count() * x) is invalid because the values transformation and count action cannot be performed inside of the rdd1.map transformationFor more information, see SPARK-5063. I've played with this a bit, and it seems to reliably occur anytime I try to map a class method to an RDD within the class. I have confirmed that the mapped function works fine if I implement outside of a class structure, so the problem definitely has to do with the class.Aug 5, 2020 · I am trying to write a function in Azure databricks. I would like to spark.sql inside the function. But it looks like I cannot use it with worker nodes. def SEL_ID(value, index): # some processing on value here ans = spark.sql("SELECT id FROM table WHERE bin = index") return ans spark.udf.register("SEL_ID", SEL_ID) PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063.Aug 21, 2017 · I downloaded a file and now I'm trying to write it as a dataframe to hdfs. import requests from pyspark import SparkContext, SparkConf conf = SparkConf().setAppName('Write Data').setMaster('loca... this rdd lacks a sparkcontext. it could happen in the following cases: . rdd transformations and actions are not invoked by the driver, . but inside of other transformations; for example, rdd1.map(x => rdd2.values.count() * x) is invalid because the values transformation and count action cannot be performed inside of the rdd1.map transformation 3. Spark RDD Broadcast variable example. Below is a very simple example of how to use broadcast variables on RDD. This example defines commonly used data (country and states) in a Map variable and distributes the variable using SparkContext.broadcast () and then use these variables on RDD map () transformation. 4. The issue is that, as self._mapping appears in the function addition, when applying addition_udf to the pyspark dataframe, the object self (i.e. the AnimalsToNumbers class) has to be serialized but it can’t be. A (surprisingly simple) way is to create a reference to the dictionary ( self._mapping) but not the object: AnimalsToNumbers (spark ...So when you say it should execute self.decode_module() inside the nodes, PySpark tries to pickle the whole (self) object (that contains a reference to the spark context). To fix that, you just need to remove the SparkContext reference from the telco_cn class and use a different approach like using the SparkContext before calling the class ...Jul 24, 2020 · For more information, see SPARK-5063. 5 results = train_and_evaluate (temp) init (self, fn, *args, **kwargs) init init (self, fn, *args, **kwargs) --> 788 self.fn = pickler.loads (pickler.dumps (self.fn)) --> 258 s = dill.dumps (o) For more information, see SPARK-5063. edit: It seems the issue is that sklearn cross_validate() clones the estimator for each fit in a fashion similar to pickling the estimator object which is not allowed for PySpark GridsearchCV estimator because a SparkContext() object cannot/should not be pickled.RDD transformations and actions can only be invoked by the driver, not inside of other transformations; for example, rdd1.map(lambda x: rdd2.values.count() * x) is invalid because the values transformation and count action cannot be performed inside of the rdd1.map transformation. For more information, see SPARK-5063. May 2, 2015 · For more information, see SPARK-5063. As the error says, i'm trying to map (transformation) a JavaRDD object within the main map function, how is it possible with Apache Spark? The main JavaPairRDD object (TextFile and Word are defined classes): JavaPairRDD<TextFile, JavaRDD<Word>> filesWithWords = new... and map function: For more information, see SPARK-5063. The objective of this piece of code is to create a flag for every row based on the date differences. Multiple rows per user are supplied to the function to create the values of the flag.Spark nested transformations SPARK-5063. I am trying to get a filtered list of list of auctions around the time of specific winning auctions while using spark. The winning auction RDD, and the full auctions DD is made up of case classes with the format: I would like to filter the full auctions RDD where auctions occurred within 10 seconds of ...Jul 14, 2015 · Spark: Broadcast variables: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transforamtion. 0. I want to broadcast a hashmap in Python that I would like to use for lookups on worker nodes. class datatransform: # Constructor def __init__(self, lookupFileName, dataFileName): ...Details. _pickle.PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063.Using foreach to fill a list from Pyspark data frame. foreach () is used to iterate over the rows in a PySpark data frame and using this we are going to add the data from each row to a list. The foreach () function is an action and it is executed on the driver node and not on the worker nodes. This means that it is not recommended to use ...For more information, see SPARK-5063. apache-spark; apache-spark-sql; pyspark; Share. Improve this question. Follow edited Sep 30, 2019 at 2:52. Pyspark Developer. with mlflow.start_run (run_name="SomeModel_run"): model = SomeModel () mlflow.pyfunc.log_model ("somemodel", python_model=model) RuntimeError: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers.May 25, 2022 · PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. def localCheckpoint (self): """ Mark this RDD for local checkpointing using Spark's existing caching layer. This method is for users who wish to truncate RDD lineages while skipping the expensive step of replicating the materialized data in a reliable distributed file system.Jan 3, 2022 · SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. from pyspark import SparkContext from awsglue.context import GlueContext from awsglue.transforms import SelectFields import ray import settings sc = SparkContext.getOrCreate () glue_context = GlueContext (sc) @ray.remote def ... Teams. Q&A for work. Connect and share knowledge within a single location that is structured and easy to search. Learn more about TeamsException: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. #88Dec 11, 2020 · Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. I also tried with the following (simple) neural network and command, and I receive EXACTLY the same error RuntimeError: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. Could I please get some help figuring this out? Thanks in advance!Jan 16, 2019 · Details. _pickle.PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. 2. Think about Spark Broadcast variable as a Python simple data type like list, So the problem is how to pass a variable to the UDF functions. Here is an example: Suppose we have ages list d and a data frame with columns name and age. So we want to check if the age of each person is in ages list.Aug 21, 2017 · I downloaded a file and now I'm trying to write it as a dataframe to hdfs. import requests from pyspark import SparkContext, SparkConf conf = SparkConf().setAppName('Write Data').setMaster('loca... Apache Spark. Databricks Runtime 10.4 LTS includes Apache Spark 3.2.1. This release includes all Spark fixes and improvements included in Databricks Runtime 10.3 (Unsupported), as well as the following additional bug fixes and improvements made to Spark: [SPARK-38322] [SQL] Support query stage show runtime statistics in formatted explain mode.Jan 21, 2019 · Thread Pools. One of the ways that you can achieve parallelism in Spark without using Spark data frames is by using the multiprocessing library. The library provides a thread abstraction that you can use to create concurrent threads of execution. However, by default all of your code will run on the driver node. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. For understanding a bit better what I am trying to do, let me give an example illustrating a possible use case : Lets say given_df is a dataframe of sentences, where each sentence consist of some words separated by space.Apr 23, 2015 · SPARK-5063 relates to better error messages when trying to nest RDD operations, which is not supported. It's a usability issue, not a functional one. The root cause is the nesting of RDD operations and the solution is to break that up. Here we are trying a join of dRDD and mRDD. For more information, see SPARK-5063. 5 results = train_and_evaluate (temp) init (self, fn, *args, **kwargs) init init (self, fn, *args, **kwargs) --> 788 self.fn = pickler.loads (pickler.dumps (self.fn)) --> 258 s = dill.dumps (o)For more information, see SPARK-5063. apache-spark; apache-spark-sql; pyspark; Share. Improve this question. Follow edited Sep 30, 2019 at 2:52. Pyspark Developer.Thread Pools. One of the ways that you can achieve parallelism in Spark without using Spark data frames is by using the multiprocessing library. The library provides a thread abstraction that you can use to create concurrent threads of execution. However, by default all of your code will run on the driver node.

Mar 26, 2020 · For more information, see SPARK-5063. 原因： spark不允许在action或transformation中访问SparkContext，如果你的action或transformation中引用了self，那么spark会将整个对象进行序列化，并将其发到工作节点上，这其中就保留了SparkContext，即使没有显式的访问它，它也会在闭包内被引用 ... . Bp a0224

For more information, see SPARK-5063. During handling of the above exception, another exception occurred: raise pickle.PicklingError(msg) _pickle.PicklingError: Could not serialize broadcast: RuntimeError: It appears that you are attempting to reference SparkContext from a broadcast variable, .. etcJan 1, 2007 · This item: Denso (5063) K20TXR Traditional Spark Plug, Pack of 1. $674. +. Powerbuilt 12 Millimeter 7-1/2-Inch Jam Nut Valve Adjustment Tool, Slotted Valve Adjusting Stud, Honda, Nissan, Toyota Vehicle Engines - 648828. $2697. Jul 27, 2021 · For more information, see SPARK-5063. The objective of this piece of code is to create a flag for every row based on the date differences. Multiple rows per user are supplied to the function to create the values of the flag. Error: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063.Description Spark does not support nested RDDs or performing Spark actions inside of transformations; this usually leads to NullPointerExceptions (see SPARK-718 as one example). The confusing NPE is one of the most common sources of Spark questions on StackOverflow: May 27, 2017 · broadcast [T] (value: T) (implicit arg0: ClassTag [T]): Broadcast [T] Broadcast a read-only variable to the cluster, returning a org.apache.spark.broadcast.Broadcast object for reading it in distributed functions. The variable will be sent to each cluster only once. You can only broadcast a real value, but an RDD is just a container of values ... For more information, see SPARK-5063. · Issue #88 · maxpumperla/elephas · GitHub maxpumperla / elephas Public Closed on Jun 26, 2018 · 18 comments mohaimenz on Jun 26, 2018Jan 3, 2018 · For more information, see SPARK-5063. (2) When a Spark Streaming job recovers from checkpoint, this exception will be hit if a reference to an RDD not defined by the streaming job is used in DStream operations. For more information, See SPARK-13758. Not working even after I revoked it and I'm not using any objects. Code Updated: 3. Spark RDD Broadcast variable example. Below is a very simple example of how to use broadcast variables on RDD. This example defines commonly used data (country and states) in a Map variable and distributes the variable using SparkContext.broadcast () and then use these variables on RDD map () transformation. 4. Jan 21, 2019 · Thread Pools. One of the ways that you can achieve parallelism in Spark without using Spark data frames is by using the multiprocessing library. The library provides a thread abstraction that you can use to create concurrent threads of execution. However, by default all of your code will run on the driver node. Jan 16, 2019 · Details. _pickle.PicklingError: Could not serialize object: Exception: It appears that you are attempting to reference SparkContext from a broadcast variable, action, or transformation. SparkContext can only be used on the driver, not in code that it run on workers. For more information, see SPARK-5063. def pickleFile (self, name: str, minPartitions: Optional [int] = None)-> RDD [Any]: """ Load an RDD previously saved using :meth:`RDD.saveAsPickleFile` method... versionadded:: 1.1.0 Parameters-----name : str directory to the input data files, the path can be comma separated paths as a list of inputs minPartitions : int, optional suggested minimum number of partitions for the resulting RDD ...May 2, 2015 · For more information, see SPARK-5063. As the error says, i'm trying to map (transformation) a JavaRDD object within the main map function, how is it possible with Apache Spark? The main JavaPairRDD object (TextFile and Word are defined classes): JavaPairRDD<TextFile, JavaRDD<Word>> filesWithWords = new... and map function: .

Popular Topics