# How to Check Which Object Cause TypeError: cannot pickle '\_thread.RLock' object?

**URL:** <https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953>\
**Category:** Uncategorized\
**Created:** [February 21, 2021, 12:38am UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953 "2021-02-21T00:38:51Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![ChihweiLHBird](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/chihweilhbird/32/496_2.png) [@ChihweiLHBird](https://discuss.ray.io/u/ChihweiLHBird)\
**Post date:** [February 21, 2021, 12:38am UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/1 "2021-02-21T00:38:51Z")

</div>

Hey,

I am trying to build a distributed spider with scrapy and ray framework. I got the following error after puting my spider into different process. I am wondering if there is a way to check which object cause this error. Any idea about debugging it? Thanks!

```auto
  File "python/ray/_raylet.pyx", line 490, in ray._raylet.execute_task
  File "python/ray/_raylet.pyx", line 491, in ray._raylet.execute_task
  File "python/ray/_raylet.pyx", line 1432, in ray._raylet.CoreWorker.store_task_outputs
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/serialization.py", line 406, in serialize
    return self._serialize_to_msgpack(value)
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/serialization.py", line 386, in _serialize_to_msgpack
    self._serialize_to_pickle5(metadata, python_objects)
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/serialization.py", line 346, in _serialize_to_pickle5
    raise e
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/serialization.py", line 342, in _serialize_to_pickle5
    inband = pickle.dumps(
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/cloudpickle/cloudpickle_fast.py", line 73, in dumps
    cp.dump(obj)
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/cloudpickle/cloudpickle_fast.py", line 574, in dump
    return Pickler.dump(self, obj)
TypeError: cannot pickle '_thread.RLock' object

```

---

<div class="post-metadata">

**Author:** ![sangcho](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/sangcho/32/425_2.png) [@sangcho](https://discuss.ray.io/u/sangcho)\
**Post date:** [February 21, 2021, 2:16am UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/2 "2021-02-21T02:16:03Z")

</div>

Hey @ChihweiLHBird great question 🙂 !!

I think from ray 1.2.0, we give you an inspection tool to test this; [https://docs.ray.io/en/master/serialization.html#troubleshooting](https://docs.ray.io/en/master/serialization.html#troubleshooting)

Please let us know after you try this out!

Also, just note that the error indicates you have a lock object in your remote method that’s serialized. Lock objects are famous by “unserializable”. The common cause is like this;

```auto
object_a = create_object_a() # Let's say this object contains a lock
@ray.remote
def f():
    return object_a # object_a is captured to this remote method!! If it has a lock, the function cannot be serialized.

```

Instead you can

```auto
object_a = create_object_a()
@ray.remote
def f(object_a): # pass object_a explicitly, so that it doesn't need to be captured and serialized
    return object_a

f.remote(object_a)

```

---

<div class="post-metadata">

**Author:** ![ChihweiLHBird](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/chihweilhbird/32/496_2.png) [@ChihweiLHBird](https://discuss.ray.io/u/ChihweiLHBird)\
**Post date:** [February 23, 2021, 11:21pm UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/3 "2021-02-23T23:21:12Z")

</div>

Thank you, Sang. I finally figure out what the unserializable object is. It is a function inside `twisted` package. For some reason, maybe because of complicated mechanism inside `twisted` and `scrapy` packages, the ray inspect tool was not able to find the unserializable object directly, lol. If you would like to know the detailed information, please let me know.

---

<div class="post-metadata">

**Author:** ![rliaw](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/rliaw/32/24_2.png) [@rliaw](https://discuss.ray.io/u/rliaw)\
**Post date:** [February 24, 2021, 1:14am UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/4 "2021-02-24T01:14:31Z")

</div>

Hmm, that’s unfortunate! Could you post the message output by `inspect_serializable`?

---

<div class="post-metadata">

**Author:** ![ChihweiLHBird](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/chihweilhbird/32/496_2.png) [@ChihweiLHBird](https://discuss.ray.io/u/ChihweiLHBird)\
**Post date:** [February 28, 2021, 9:05pm UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/5 "2021-02-28T21:05:16Z")

</div>

Source code:

```auto
import ray
import scrapy
from scrapy.utils.project import get_project_settings
from scrapy.crawler import CrawlerProcess

ray.init()

@ray.remote
class DistributedCrawlerProcess(CrawlerProcess):
    pass

class QuotesSpider(scrapy.Spider):
    name = "quotes"

    def start_requests(self):
        urls = [
            'http://quotes.toscrape.com/page/1/',
            'http://quotes.toscrape.com/page/2/',
        ]
        for url in urls:
            yield scrapy.Request(url=url, callback=self.parse)

    def parse(self, response):
        pass

if __name__ == " __main__":
    from ray.util import inspect_serializability
    inspect_serializability(DistributedCrawlerProcess, name="test")
    inspect_serializability(DistributedCrawlerProcess.crawl, name="test")
    inspect_serializability(DistributedCrawlerProcess.start, name="test")
    inspect_serializability(QuotesSpider, name="test")

    num_parallel_processes = 1 # Can be changed to more.

    ray_obj_list = []
    for i in range(num_parallel_processes):
        settings = get_project_settings()
        process = DistributedCrawlerProcess.remote(settings)
        process.crawl.remote(QuotesSpider)
        ray_obj_list.append(process.start.remote())

    ray.get(ray_obj_list)

```

Output:

```auto
2021-02-28 14:04:19,617 INFO services.py:1172 -- View the Ray dashboard at http://127.0.0.1:8265
================================================================================
Checking Serializability of < __main__.ActorClass(DistributedCrawlerProcess) object at 0x7f92b0493040>
================================================================================
================================================================================
Checking Serializability of <bound method CrawlerRunner.crawl of < __main__.ActorClass(DistributedCrawlerProcess) object at 0x7f92b0493040>>
================================================================================
================================================================================
Checking Serializability of <bound method CrawlerProcess.start of < __main__.ActorClass(DistributedCrawlerProcess) object at 0x7f92b0493040>>
================================================================================
===========================================================
Checking Serializability of <class ' __main__.QuotesSpider'>
===========================================================
(pid=26064) 2021-02-28 14:04:23 [scrapy.utils.log] INFO: Scrapy 2.4.1 started (bot: product_spiders)
(pid=26064) 2021-02-28 14:04:23 [scrapy.utils.log] INFO: Versions: lxml 4.6.2.0, libxml2 2.9.10, cssselect 1.1.0, parsel 1.6.0, w3lib 1.22.0, Twisted 20.3.0, Python 3.8.5 (default, Jul 28 2020, 12:59:40) - [GCC 9.3.0], pyOpenSSL 20.0.1 (OpenSSL 1.1.1j 16 Feb 2021), cryptography 3.4.6, Platform Linux-5.4.72-microsoft-standard-WSL2-x86_64-with-glibc2.29
(pid=26064) 2021-02-28 14:04:23 [scrapy.utils.log] DEBUG: Using reactor: twisted.internet.epollreactor.EPollReactor
(pid=26064) 2021-02-28 14:04:23 [scrapy.crawler] INFO: Overridden settings:
(pid=26064) {'AUTOTHROTTLE_ENABLED': True,
(pid=26064) 'BOT_NAME': 'product_spiders',
(pid=26064) 'COOKIES_ENABLED': False,
(pid=26064) 'DOWNLOAD_DELAY': 0.5,
(pid=26064) 'NEWSPIDER_MODULE': 'product_spiders.spiders',
(pid=26064) 'ROBOTSTXT_OBEY': True,
(pid=26064) 'SPIDER_MODULES': ['product_spiders.spiders']}
(pid=26064) 2021-02-28 14:04:23 [scrapy.extensions.telnet] INFO: Telnet Password: 356900ad59191af5
(pid=26064) 2021-02-28 14:04:23 [scrapy.middleware] INFO: Enabled extensions:
(pid=26064) ['scrapy.extensions.corestats.CoreStats',
(pid=26064) 'scrapy.extensions.telnet.TelnetConsole',
(pid=26064) 'scrapy.extensions.memusage.MemoryUsage',
(pid=26064) 'scrapy.extensions.logstats.LogStats',
(pid=26064) 'scrapy.extensions.throttle.AutoThrottle']
(pid=26064) 2021-02-28 14:04:23 [scrapy.middleware] INFO: Enabled downloader middlewares:
(pid=26064) ['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.retry.RetryMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware',
(pid=26064) 'scrapy.downloadermiddlewares.stats.DownloaderStats']
(pid=26064) 2021-02-28 14:04:23 [scrapy.middleware] INFO: Enabled spider middlewares:
(pid=26064) ['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
(pid=26064) 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
(pid=26064) 'scrapy.spidermiddlewares.referer.RefererMiddleware',
(pid=26064) 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
(pid=26064) 'scrapy.spidermiddlewares.depth.DepthMiddleware']
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from creating-client-class.iot-data to creating-client-class.iot-data-plane
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from before-call.apigateway to before-call.api-gateway
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from request-created.machinelearning.Predict to request-created.machine-learning.Predict
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from before-parameter-build.autoscaling.CreateLaunchConfiguration to before-parameter-build.auto-scaling.CreateLaunchConfiguration
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from before-parameter-build.route53 to before-parameter-build.route-53
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from request-created.cloudsearchdomain.Search to request-created.cloudsearch-domain.Search
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from docs.*.autoscaling.CreateLaunchConfiguration.complete-section to docs.*.auto-scaling.CreateLaunchConfiguration.complete-section
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from before-parameter-build.logs.CreateExportTask to before-parameter-build.cloudwatch-logs.CreateExportTask
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from docs.*.logs.CreateExportTask.complete-section to docs.*.cloudwatch-logs.CreateExportTask.complete-section
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from before-parameter-build.cloudsearchdomain.Search to before-parameter-build.cloudsearch-domain.Search
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Changing event name from docs.*.cloudsearchdomain.Search.complete-section to docs.*.cloudsearch-domain.Search.complete-section
(pid=26064) 2021-02-28 14:04:23 [botocore.loaders] DEBUG: Loading JSON file: /home/chihwei/.local/lib/python3.8/site-packages/boto3/data/dynamodb/2012-08-10/resources-1.json
(pid=26064) 2021-02-28 14:04:23 [botocore.loaders] DEBUG: Loading JSON file: /home/chihwei/.local/lib/python3.8/site-packages/botocore/data/endpoints.json
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event choose-service-name: calling handler <function handle_service_name_alias at 0x7f5932d0e040>
(pid=26064) 2021-02-28 14:04:23 [botocore.loaders] DEBUG: Loading JSON file: /home/chihwei/.local/lib/python3.8/site-packages/botocore/data/dynamodb/2012-08-10/service-2.json
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-client-class.dynamodb: calling handler <function add_generate_presigned_url at 0x7f5932d3fdc0>
(pid=26064) 2021-02-28 14:04:23 [botocore.endpoint] DEBUG: Setting dynamodb timeout as (60, 60)
(pid=26064) 2021-02-28 14:04:23 [botocore.loaders] DEBUG: Loading JSON file: /home/chihwei/.local/lib/python3.8/site-packages/botocore/data/_retry.json
(pid=26064) 2021-02-28 14:04:23 [botocore.client] DEBUG: Registering retry handlers for service: dynamodb
(pid=26064) 2021-02-28 14:04:23 [boto3.resources.factory] DEBUG: Loading dynamodb:dynamodb
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.ServiceResource: calling handler <function lazy_call.<locals>._handler at 0x7f5931020ee0>
(pid=26064) 2021-02-28 14:04:23 [boto3.resources.factory] DEBUG: Loading dynamodb:Table
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.Table: calling handler <function lazy_call.<locals>._handler at 0x7f5931020f70>
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.Table: calling handler <function lazy_call.<locals>._handler at 0x7f5931020ee0>
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event choose-service-name: calling handler <function handle_service_name_alias at 0x7f5932d0e040>
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-client-class.dynamodb: calling handler <function add_generate_presigned_url at 0x7f5932d3fdc0>
(pid=26064) 2021-02-28 14:04:23 [botocore.endpoint] DEBUG: Setting dynamodb timeout as (60, 60)
(pid=26064) 2021-02-28 14:04:23 [botocore.client] DEBUG: Registering retry handlers for service: dynamodb
(pid=26064) 2021-02-28 14:04:23 [boto3.resources.factory] DEBUG: Loading dynamodb:dynamodb
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.ServiceResource: calling handler <function lazy_call.<locals>._handler at 0x7f5931020ee0>
(pid=26064) 2021-02-28 14:04:23 [boto3.resources.factory] DEBUG: Loading dynamodb:Table
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.Table: calling handler <function lazy_call.<locals>._handler at 0x7f5931020f70>
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.Table: calling handler <function lazy_call.<locals>._handler at 0x7f5931020ee0>
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event choose-service-name: calling handler <function handle_service_name_alias at 0x7f5932d0e040>
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-client-class.dynamodb: calling handler <function add_generate_presigned_url at 0x7f5932d3fdc0>
(pid=26064) 2021-02-28 14:04:23 [botocore.endpoint] DEBUG: Setting dynamodb timeout as (60, 60)
(pid=26064) 2021-02-28 14:04:23 [botocore.client] DEBUG: Registering retry handlers for service: dynamodb
(pid=26064) 2021-02-28 14:04:23 [boto3.resources.factory] DEBUG: Loading dynamodb:dynamodb
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.ServiceResource: calling handler <function lazy_call.<locals>._handler at 0x7f5931020ee0>
(pid=26064) 2021-02-28 14:04:23 [boto3.resources.factory] DEBUG: Loading dynamodb:Table
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.Table: calling handler <function lazy_call.<locals>._handler at 0x7f5931020f70>
(pid=26064) 2021-02-28 14:04:23 [botocore.hooks] DEBUG: Event creating-resource-class.dynamodb.Table: calling handler <function lazy_call.<locals>._handler at 0x7f5931020ee0>
(pid=26064) 2021-02-28 14:04:23 [scrapy.middleware] INFO: Enabled item pipelines:
(pid=26064) ['product_spiders.pipelines.UpdateDatabasePipeline']
(pid=26064) 2021-02-28 14:04:23 [scrapy.core.engine] INFO: Spider opened
(pid=26064) 2021-02-28 14:04:23 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
(pid=26064) 2021-02-28 14:04:23 [scrapy.extensions.telnet] INFO: Telnet console listening on 127.0.0.1:6023
(pid=26064) 2021-02-28 14:04:23 [scrapy.core.engine] DEBUG: Crawled (404) <GET http://quotes.toscrape.com/robots.txt> (referer: None)
2021-02-28 14:04:28,238 ERROR worker.py:1053 -- Possible unhandled error from worker: ray::DistributedCrawlerProcess.crawl() (pid=26064, ip=172.31.171.50)
  File "python/ray/_raylet.pyx", line 509, in ray._raylet.execute_task
  File "python/ray/_raylet.pyx", line 510, in ray._raylet.execute_task
  File "python/ray/_raylet.pyx", line 1466, in ray._raylet.CoreWorker.store_task_outputs
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/serialization.py", line 319, in serialize
    return self._serialize_to_msgpack(value)
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/serialization.py", line 299, in _serialize_to_msgpack
    self._serialize_to_pickle5(metadata, python_objects)
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/serialization.py", line 259, in _serialize_to_pickle5
    raise e
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/serialization.py", line 255, in _serialize_to_pickle5
    inband = pickle.dumps(
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/cloudpickle/cloudpickle_fast.py", line 73, in dumps
    cp.dump(obj)
  File "/home/chihwei/.local/lib/python3.8/site-packages/ray/cloudpickle/cloudpickle_fast.py", line 574, in dump
    return Pickler.dump(self, obj)
TypeError: cannot pickle '_thread.RLock' object
(pid=26064) 2021-02-28 14:04:29 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://quotes.toscrape.com/page/1/> (referer: None)
(pid=26064) 2021-02-28 14:04:36 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://quotes.toscrape.com/page/2/> (referer: None)
(pid=26064) 2021-02-28 14:04:36 [scrapy.core.engine] INFO: Closing spider (finished)
(pid=26064) 2021-02-28 14:04:36 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
(pid=26064) {'downloader/request_bytes': 681,
(pid=26064) 'downloader/request_count': 3,
(pid=26064) 'downloader/request_method_count/GET': 3,
(pid=26064) 'downloader/response_bytes': 5642,
(pid=26064) 'downloader/response_count': 3,
(pid=26064) 'downloader/response_status_count/200': 2,
(pid=26064) 'downloader/response_status_count/404': 1,
(pid=26064) 'elapsed_time_seconds': 13.422068,
(pid=26064) 'finish_reason': 'finished',
(pid=26064) 'finish_time': datetime.datetime(2021, 2, 28, 21, 4, 36, 641320),
(pid=26064) 'log_count/DEBUG': 45,
(pid=26064) 'log_count/INFO': 10,
(pid=26064) 'memusage/max': 126164992,
(pid=26064) 'memusage/startup': 126164992,
(pid=26064) 'response_received_count': 3,
(pid=26064) 'robotstxt/request_count': 1,
(pid=26064) 'robotstxt/response_count': 1,
(pid=26064) 'robotstxt/response_status_count/404': 1,
(pid=26064) 'scheduler/dequeued': 2,
(pid=26064) 'scheduler/dequeued/memory': 2,
(pid=26064) 'scheduler/enqueued': 2,
(pid=26064) 'scheduler/enqueued/memory': 2,
(pid=26064) 'start_time': datetime.datetime(2021, 2, 28, 21, 4, 23, 219252)}
(pid=26064) 2021-02-28 14:04:36 [scrapy.core.engine] INFO: Spider closed (finished)

```

---

<div class="post-metadata">

**Author:** ![rliaw](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/rliaw/32/24_2.png) [@rliaw](https://discuss.ray.io/u/rliaw)\
**Post date:** [March 1, 2021, 8:47am UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/6 "2021-03-01T08:47:21Z")

</div>

Oh, got it; it looks like the response object (`scrapy.Request(url=url, callback=self.parse)`) is non-serializable…

---

<div class="post-metadata">

**Author:** ![ChihweiLHBird](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/chihweilhbird/32/496_2.png) [@ChihweiLHBird](https://discuss.ray.io/u/ChihweiLHBird)\
**Post date:** [March 8, 2021, 7:14am UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/7 "2021-03-08T07:14:32Z")

</div>

It seems still fail to check the serializability of the Request object…

```auto
inspect_serializability(scrapy.Request, name="test")
inspect_serializability(scrapy.Request(url="https://www.google.com/"), name="test")

```

```auto
=================================================================
Checking Serializability of <class 'scrapy.http.request.Request'>
=================================================================
=========================================================
Checking Serializability of <GET https://www.google.com/>
=========================================================

```

---

<div class="post-metadata">

**Author:** ![ChihweiLHBird](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/chihweilhbird/32/496_2.png) [@ChihweiLHBird](https://discuss.ray.io/u/ChihweiLHBird)\
**Post date:** [March 8, 2021, 7:36am UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/8 "2021-03-08T07:36:24Z")

</div>

May I explore the way to detect this kind of non-serializable issue? I can shares details here if I can figure it out.

---

<div class="post-metadata">

**Author:** ![rliaw](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/rliaw/32/24_2.png) [@rliaw](https://discuss.ray.io/u/rliaw)\
**Post date:** [March 8, 2021, 9:13pm UTC](https://discuss.ray.io/t/how-to-check-which-object-cause-typeerror-cannot-pickle-thread-rlock-object/953/9 "2021-03-08T21:13:55Z")

</div>

Hmm, well one possibility is to just call `pickle.dumps(object)`, and then check all the attributes + scope of the object, and narrow down the scope of the object manually/iteratively.